perf: use a hashmap when possible for file extension matching

[5225225]

This shouldn't affect behavior in any way, since glob patterns of the form *.foo / *.bar are disjoint, so it doesn't matter which order we search them in.

The exact order of disjoint patterns like that aren't preserved anymore, so the test suite needed to change a bit.

hyperfine "./target/release/eza --color=always /nix/store" on 3ad8132 gets

Benchmark 1: ./target/release/eza --color=always /nix/store
Time (mean ± σ): 5.109 s ± 0.488 s [User: 4.682 s, System: 0.383 s]
Range (min … max): 4.691 s … 6.262 s 10 runs

when on this branch (d2ff56b), it is

Benchmark 1: ./target/release/eza --color=always /nix/store
Time (mean ± σ): 724.7 ms ± 6.3 ms [User: 379.4 ms, System: 339.9 ms]
Range (min … max): 714.7 ms … 733.0 ms 10 runs

(and for reference: ls /nix/store | wc -l is 77967)

I didn't want to add any new dependencies, but Simple probably should be using a small string. This is definitely an improvement as-is though.