Add support for case-insensitive matching to Levenshtein DFAs

Adds matching modes `Cased` and `Uncased`.

`Cased` requires UTF-32 code points to match exactly, and successor
strings are guaranteed to be strictly higher than the source (candidate)
string in `memcmp` order. This mirrors the behavior of the current
DFA implementation.

`Uncased` treats all characters as if they were lowercased, both
for the target and source strings. The target (query) string is
explicitly lowercased at DFA build-time to avoid duplicate work.
Source strings are implicitly lowercased character by character
on-demand during matching.

Important ordering note: Successor strings for `Uncased` are generated
_as if_ the source string was originally all in lowercase form.
This requires some extra added handling when emitting successor
prefixes, as we can't just blindly copy UTF-8 bytes from the source
string as we do when matching in `Cased` mode.

A new casing-dimension has been added to most parameterized unit
tests.

0 files changed, 0 insertions, 0 deletions