Add inline_comment_spaces formatter option

[ChrisJr404]

Closes #469.

Adds an inline_comment_spaces formatter option to control how many spaces go before a trailing comment on the same line as an entry or array item, similar to PEP 8's two-space convention. It defaults to 1, so existing output is unchanged, and it only kicks in when the comment isn't being aligned by align_comments (the alignment logic already handles spacing in that case).

The spacing is applied in format_rows by overriding the separator used before the comment column, so it covers both entry comments and array item comments. Added two formatter tests (one for the new spacing, one asserting the default stays a single space) and a row in the formatter options docs.