[ty] Optimize query string matching
While this doesn't typically matter, when ty returns a very
large list of symbols, this can have an impact. Specifically,
when searching `async` in home-assistant, this gets times
closer to 500ms versus closer to 600ms before this change.
It looks like an overall ~50ms improvement (so around 10%),
but variance is all over the place and I didn't do any
statistical tests.
But this does make intuitive sense. Previously, we were
allocating intermediate strings, doing UTF-8 decoding and
consulting Unicode casing tables. Now we're just doing what
is likely a single DFA scan. In effect, we front load all
of the Unicode junk into regex compilation.
