Recommit changes to global checks (#71171)

Recommits the changes from https://reviews.llvm.org/D148216.
Explicitly named globals are now matched literally, instead of emitting
a capture group for the name. This resolves #70047.
Metadata and annotations, on the other hand, are captured and matched
against by default, since their identifiers are not stable.

The reasons for revert (#63746) have been fixed:
The first issue, that of duplicated checkers, has already been resolved
in #70050.
This PR resolves the second issue listed in #63746, regarding the order
of named and unnamed globals. This is fixed by recording the index of
substrings containing global values, and sorting the checks according to
that index before emitting them. This results in global value checks
being emitted in the order they were seen instead of being grouped
separately.