Patch - Core: Break words in paragraphs and headings only (#2467)

* Theme: Set word-break to initial for table children

#2450 added a CSS selector that set the word-break property to break-word anywhere within the main element.

But it had unexpected side effects in certain kinds of two-dimensional content, such as tables. Specifically, it could cause wide tables (even ones situated within table-responsive containers) to divide their columns improperly - resulting in individual numbers in number groupings "splitting" across lines, columns that are too narrow to fit short words on the same line, non-breaking spaces getting ignored, etc...

This resolves it by adding overrides to reset the word-break properties of any table child elements to initial.

Fixes #2466.

* Update sites/baseline/_scaffolding.scss

Co-authored-by: Garneauma <garneauma@gmail.com>

* Set word-break to initial for paragraphs in table cells
* Prevents improper column division in cells containing paragraphs with long text (e.g. large dollar amounts, publication numbers, year ranges, etc...)
* Retains break-word in paragraphs situated within table captions
* Leverages a placeholder selector

---------

Co-authored-by: Garneauma <garneauma@gmail.com>

sites/baseline/_scaffolding.scss

@@ -7,6 +7,10 @@
  *
  */
 
+%gcweb-scaffolding-word-break-break-word {
+	word-break: break-word;
+}
+
 //
 // Apply baseline font styling
 // For the font smooth, read the justification here: https://wet-boew.github.io/themes-dist/GCWeb/gcweb-theme/index.html#antialiasing
@@ -21,8 +25,20 @@ main {
 	font-size: 20px;
 	line-height: 1.65em;
 
-	* {
-		word-break: break-word;
+	h1, h2, h3, h4, h5, h6, p {
+		@extend %gcweb-scaffolding-word-break-break-word;
+	}
+
+	table {
+		caption {
+			p {
+				@extend %gcweb-scaffolding-word-break-break-word;
+			}
+		}
+
+		p {
+			word-break: initial;
+		}
 	}
 }