[records] Disambiguate metadata annotation arguments and record types.

[munificent]

Fix #2469.

[jensjoha]

Can we please not do the

Comments do not count as whitespace,
nor do whitespace characters in comments. The newline at the end of a line
comment *does* count as whitespace.

part?

Currently the parser does not have to worry about comments at all. In fact it's an option to the scanner to not save them at all to save memory and time. In fact that's what the CFE does. We don't need them and don't waste time and space on them.

From #2469 (comment)

I'm very tempted to say that if the next source token (ignoring comments and whitespace) after the identifier does not start right where the identifier ends, it's not part of the annotation. So no comments either.

Can we have that instead please?

[munificent]

I've updated the proposal to clarify that the parser changes are not language versioned. Reviewer friends, does this look ready to land?

[lrhn]

LGTM