fix(msg): use python-oxmsg for MSG email parsing

`partition_msg()` previously used the `msg_parser` library for parsing
Outlook MSG email files (.msg files). The `msg_parser` library is
unmaintained and has several major shortcomings such as not being able
to parse MSG files with 8-bit encoded strings and not reliably
extracting attachments.

Use the new and permissively licenced `python-oxmsg` library instead.

For reviewability purposes, this PR temporarily places the new
`partition_msg()` implementation in `new_msg.py` and references that
implementation from `msg.py`. `new_msg.py` will be renamed to `msg.py`
in a closely following PR. This avoids a very messing interleaving of
hunks in a diff between the old and re-written new implementation.

CHANGELOG.md

@@ -1,3 +1,16 @@
+## 0.14.5-dev0
+
+### Enhancements
+
+* **Use `python-oxmsg` for `partition_msg()`.** Outlook MSG emails are now partitioned using the `python-oxmsg` package which resolves some shortcomings of the prior MSG parser.
+
+### Features
+
+### Fixes
+
+* **8-bit string Outlook MSG files are parsed.** `partition_msg()` is now able to parse non-unicode Outlook MSG emails.
+* **Attachments to Outlook MSG files are extracted intact.** `partition_msg()` is now able to extract attachments without corruption.
+
 ## 0.14.4
 
 ### Enhancements

pyproject.toml

@@ -31,6 +31,7 @@ lint.select = [
 ]
 lint.ignore = [
     "COM812",   # -- over aggressively insists on trailing commas where not desireable --
+    "PT001",    # -- wants empty parens on @pytest.fixture where not used (essentially always) --
     "PT005",    # -- flags mock fixtures with names intentionally matching private method name --
     "PT011",    # -- pytest.raises({exc}) too broad, use match param or more specific exception --
     "PT012",    # -- pytest.raises() block should contain a single simple statement --

requirements/extra-msg.in

@@ -1,4 +1,4 @@
 -c ./deps/constraints.txt
 -c base.txt
 
-msg_parser
+python-oxmsg

requirements/extra-msg.txt

@@ -4,7 +4,15 @@
 #
 #    pip-compile ./extra-msg.in
 #
-msg-parser==1.2.0
-    # via -r ./extra-msg.in
+click==8.1.7
+    # via
+    #   -c ./base.txt
+    #   python-oxmsg
 olefile==0.47
-    # via msg-parser
+    # via python-oxmsg
+python-oxmsg==0.0.1
+    # via -r ./extra-msg.in
+typing-extensions==4.12.0
+    # via
+    #   -c ./base.txt
+    #   python-oxmsg