Fix inline for-expression matching

[dbanck]

This PR improves the inline-for regex, which used to break the highlighting of the rest of the file because it was never terminated.

In the old structure, the end: \n regex never matched the end of the line in the example, because the object repository would consume the { at the end of the line (including the newline). By changing this to a single match regex, we can now match the entire line and then delegate the second capture expression to the for_expression_body as before.

This shouldn't affect any of our existing tests related to for-expressions.

UX Before

UX After

Closes #113