Maybe 2024 changes?
Note that we now set `edition = "2024"` explicitly in `rustfmt.toml`.
Without this, it seems like it's possible in some cases for rustfmt to
run under an older edition's style. Not sure how though.
The top-level listing was just getting a bit too long for my taste. So
put all of the code in one directory and shrink the large top-level mess
to a small top-level mess.
NOTE: This commit only contains renames. The subsequent commit will
actually make ripgrep build again. We do it this way with the naive hope
that this will make it easier for git history to track the renames.
Sigh.
