Fix html escaping of source line marks

SourceFileViewHTMLGenerator escaping code had multiple issues:

- When marking each line from range_start_pragma_processor as safe, we
  wrapped not only strings but also whole tuples in Markup().
- For tuple elements we didn't differentiate whether they from pygments
  (already escaped) or from source file (not yet escaped). Only the
  later must be explicitly escaped.

Relates to #1921.

strictdoc/export/html/generators/source_file_view_generator.py

@@ -1,5 +1,5 @@
 # mypy: disable-error-code="no-untyped-call,no-untyped-def,operator"
-from typing import List, Tuple
+from typing import List, Tuple, Union
 
 from markupsafe import Markup, escape
 from pygments import highlight
@@ -89,7 +89,19 @@ def get_pygmented_source_lines(
         source_file: SourceFile,
         source_file_lines: List[str],
         coverage_info: SourceFileTraceabilityInfo,
-    ) -> Tuple[List[Markup], Markup]:
+    ) -> Tuple[
+        List[
+            Union[
+                Markup,
+                Tuple[
+                    Markup,
+                    Markup,
+                    Union[ForwardRangeMarker, LineMarker, RangeMarker],
+                ],
+            ]
+        ],
+        Markup,
+    ]:
         assert isinstance(source_file, SourceFile)
         assert isinstance(source_file_lines, list)
         assert isinstance(coverage_info, SourceFileTraceabilityInfo)
@@ -178,15 +190,18 @@ def get_pygmented_source_lines(
         for pragma in coverage_info.pragmas:
             pragma_line = pragma.ng_source_line_begin
             if isinstance(pragma, ForwardRangeMarker):
-                pygmented_source_file_lines[pragma_line - 1] = (
+                before_line = (
                     pygmented_source_file_lines[pragma_line - 1].rstrip("\n")
-                    + " ",
-                    "\n",
+                    + " "
+                )
+                pygmented_source_file_lines[pragma_line - 1] = (
+                    Markup(before_line),
+                    Markup("\n"),
                     pragma,
                 )
                 continue
 
-            source_line = source_file_lines[pragma_line - 1]
+            source_line = escape(source_file_lines[pragma_line - 1])
 
             assert len(pragma.reqs_objs) > 0
             before_line = source_line[
@@ -203,15 +218,17 @@ def get_pygmented_source_lines(
             after_line = source_line[closing_bracket_index:].rstrip()
 
             pygmented_source_file_lines[pragma_line - 1] = (
-                escape(before_line),
-                escape(after_line),
+                before_line,
+                after_line,
                 pragma,
             )
         pygments_styles = (
             f"/* Lexer: {lexer.name} */\n"
             + html_formatter.get_style_defs(".highlight")
         )
 
-        return list(map(Markup, pygmented_source_file_lines)), Markup(
-            pygments_styles
+        as_markup = map(
+            lambda l: l if isinstance(l, tuple) else Markup(l),
+            pygmented_source_file_lines,
         )
+        return list(as_markup), Markup(pygments_styles)