This doesn't add full support. I'm separating it out to make the effects
of the modifier changes clearer for review. I'm restructuring a little
with the expectation that we'll have some more categories of modifier
keywords in the future (similar to `extern`, these may not be in a "set"
such as access), and thus easily scaling up to a few more would be
useful.
This removes a (very) hot branch in the lexer where we need to special
case when a token is the first token and can't look at its previous
token. It also seems like a generally nice change to the structure of
both the token buffer and parse tree as there are now bracketing
elements for both ends and we should be able to avoid similar branching
in the future.
Mostly mechanical updates to the lexer and parser code to handle this,
but also needed to special case the location information in the
autoupdate code. And then the usual large body of auto-updated tests.
No benchmark data for this change alone as in isolation and in the
current lexer structure it doesn't make a big difference. But this
branch was particularly difficult to handle when trying to update the
whitespace skipping code to be faster, and so I think it is worth
systematically avoiding the special case here.
Continuing with #3070. Just a dir and file rename (mostly removing
prefixes, although for parse_tree_fuzzer and parse_tree_file_test I'm
dropping "tree" instead of "parse"). Everything in the parse dir should
be marked as a move.