Refactor TextBuffer::GenHTML/RTF to read the buffer directly (#16377)

`TextBuffer::GenHTML` and `TextBuffer::GenRTF` now read directly from
the TextBuffer.

- Since we're reading from the buffer, we can now read _all_ the
attributes saved in the buffer. Formatted copy now copies most (if not
all) font/color attributes in the requested format (RTF/HTML).
- Use `TextBuffer::CopyRequest` to pass all copy-related options into
text generation functions as one unit.
- Helper function `TextBuffer::CopyRequest::FromConfig()` generates a
copy request based on Selection mode and user configuration.
- Both formatted text generation functions now use `std::string` and
`fmt::format_to` to generate the required strings. Previously, we were
using `std::ostringstream` which is not recommended due to its potential
overhead.
- Reading attributes from `ROW`'s attribute RLE simplified the logic as
we don't have to track attribute change between the text.
- On the caller side, we do not have to rebuild the plain text string
from the vector of strings anymore. `TextBuffer::GetPlainText()` returns
the entire text as one `std::string`.
- Removed `TextBuffer::TextAndColors`.
- Removed `TextBuffer::GetText()`. `TextBuffer::GetPlainText()` took its
place.

This PR also fixes two bugs in the formatted copy:

- We were applying line breaks after each selected row, even though the
row could have been a Wrapped row. This caused the wrapped rows to break
when they shouldn't.
- We mishandled Unicode text (\uN) within the RTF copy. Every next
character that uses a surrogate pair or high codepoint was missing in
the copied text when pasted to MSWord. The command `\uc4` should have
been `\uc1`, which is used to tell how many fallback characters are used
for each Unicode codepoint (\u). We always use one `?` character as the
fallback.

Closes #16191

**References and Relevant Issues**

- #16270

**Validation Steps Performed**

- Casual copy-pasting from Terminal or OpenConsole to word editors works
as before.
- Verified HTML copy by copying the generated HTML string and running it
through an HTML viewer.
[Sample](https://codepen.io/tusharvickey/pen/wvNXbVN)
- Verified RTF copy by copy-pasting the generated RTF string into
MSWord.
- SingleLine mode works (<kbd>Shift</kbd>+ copy)
- BlockSelection mode works (<kbd>Alt</kbd> selection)

.github/actions/spelling/expect/expect.txt

@@ -1113,8 +1113,8 @@ msix
 msrc
 MSVCRTD
 MTSM
-munged
 munges
+Munged
 murmurhash
 muxes
 myapplet
@@ -1870,7 +1870,12 @@ uiautomationcore
 uielem
 UIELEMENTENABLEDONLY
 UINTs
+ul
 ulcch
+uld
+uldb
+uldash
+ulwave
 Unadvise
 unattend
 UNCPRIORITY

src/buffer/out/Row.cpp

@@ -404,6 +404,18 @@ til::CoordType ROW::AdjustToGlyphStart(til::CoordType column) const noexcept
     return _adjustBackward(_clampedColumn(column));
 }
 
+// Returns the (exclusive) ending column of the glyph at the given column.
+// In other words, if you have 3 wide glyphs
+//   AA BB CC
+//   01 23 45 <-- column
+// Examples:
+// - `AdjustToGlyphEnd(4)` returns 6.
+// - `AdjustToGlyphEnd(3)` returns 4.
+til::CoordType ROW::AdjustToGlyphEnd(til::CoordType column) const noexcept
+{
+    return _adjustForward(_clampedColumnInclusive(column));
+}
+
 // Routine Description:
 // - clears char data in column in row
 // Arguments:
@@ -939,6 +951,32 @@ uint16_t ROW::size() const noexcept
     return _columnCount;
 }
 
+// Routine Description:
+// - Retrieves the column that is one after the last non-space character in the row.
+til::CoordType ROW::GetLastNonSpaceColumn() const noexcept
+{
+    const auto text = GetText();
+    const auto beg = text.begin();
+    const auto end = text.end();
+    auto it = end;
+
+    for (; it != beg; --it)
+    {
+        // it[-1] is safe as `it` is always greater than `beg` (loop invariant).
+        if (til::at(it, -1) != L' ')
+        {
+            break;
+        }
+    }
+
+    // We're supposed to return the measurement in cells and not characters
+    // and therefore simply calculating `it - beg` would be wrong.
+    //
+    // An example: The row is 10 cells wide and `it` points to the second character.
+    // `it - beg` would return 1, but it's possible it's actually 1 wide glyph and 8 whitespace.
+    return gsl::narrow_cast<til::CoordType>(GetReadableColumnCount() - (end - it));
+}
+
 til::CoordType ROW::MeasureLeft() const noexcept
 {
     const auto text = GetText();
@@ -957,6 +995,8 @@ til::CoordType ROW::MeasureLeft() const noexcept
     return gsl::narrow_cast<til::CoordType>(it - beg);
 }
 
+// Routine Description:
+// - Retrieves the column that is one after the last valid character in the row.
 til::CoordType ROW::MeasureRight() const noexcept
 {
     if (_wrapForced)
@@ -969,26 +1009,7 @@ til::CoordType ROW::MeasureRight() const noexcept
         return width;
     }
 
-    const auto text = GetText();
-    const auto beg = text.begin();
-    const auto end = text.end();
-    auto it = end;
-
-    for (; it != beg; --it)
-    {
-        // it[-1] is safe as `it` is always greater than `beg` (loop invariant).
-        if (til::at(it, -1) != L' ')
-        {
-            break;
-        }
-    }
-
-    // We're supposed to return the measurement in cells and not characters
-    // and therefore simply calculating `it - beg` would be wrong.
-    //
-    // An example: The row is 10 cells wide and `it` points to the second character.
-    // `it - beg` would return 1, but it's possible it's actually 1 wide glyph and 8 whitespace.
-    return gsl::narrow_cast<til::CoordType>(_columnCount - (end - it));
+    return GetLastNonSpaceColumn();
 }
 
 bool ROW::ContainsText() const noexcept

src/buffer/out/Row.hpp

@@ -137,6 +137,7 @@ class ROW final
     til::CoordType NavigateToPrevious(til::CoordType column) const noexcept;
     til::CoordType NavigateToNext(til::CoordType column) const noexcept;
     til::CoordType AdjustToGlyphStart(til::CoordType column) const noexcept;
+    til::CoordType AdjustToGlyphEnd(til::CoordType column) const noexcept;
 
     void ClearCell(til::CoordType column);
     OutputCellIterator WriteCells(OutputCellIterator it, til::CoordType columnBegin, std::optional<bool> wrap = std::nullopt, std::optional<til::CoordType> limitRight = std::nullopt);
@@ -151,6 +152,7 @@ class ROW final
     TextAttribute GetAttrByColumn(til::CoordType column) const;
     std::vector<uint16_t> GetHyperlinks() const;
     uint16_t size() const noexcept;
+    til::CoordType GetLastNonSpaceColumn() const noexcept;
     til::CoordType MeasureLeft() const noexcept;
     til::CoordType MeasureRight() const noexcept;
     bool ContainsText() const noexcept;