bugfix(formatter): Made all single line comment prevent removing line-breaks. - #10045

Summary

Fixes the Cairo formatter incorrectly collapsing match arm bodies that contain doc comments (///) or inner comments (//!) into a single line, stripping the comment in the process. The fix updates is_statement_list_break_point_optional to check for TokenSingleLineComment, TokenSingleLineDocComment, and TokenSingleLineInnerComment syntax kinds directly, rather than walking through Trivia nodes and checking for SingleLineComment trivium variants (which did not cover doc/inner comment token kinds). A test case covering both /// and //! in match arm bodies is added.

Type of change

Please check one:

• Bug fix (fixes incorrect behavior)
• New feature
• Performance improvement
• Documentation change with concrete technical impact
• Style, wording, formatting, or typo-only change

Why is this change needed?

Match arm bodies containing doc comments (///) or inner comments (//!) were being incorrectly treated as candidates for collapsing to a single line. The previous check only recognized ast::Trivium::SingleLineComment, missing the doc and inner comment token kinds, so those comments were silently dropped when the formatter collapsed the block.

What was the behavior or documentation before?

A match arm like:

0 => {
    /// doc comment
    1
},

would be incorrectly formatted (the comment was dropped and the block collapsed).

What is the behavior or documentation after?

Match arm bodies containing /// or //! comments are preserved as multi-line blocks, keeping the comment intact:

0 => {
    /// doc comment
    1
},

Related issue or discussion (if any)

N/A

Additional context

The format_leading_comment doc comment was also updated to clarify that the formatter only merges continuation lines it broke off from over-long open lines, not lines the user wrote separately.