Perf: SourceField, PathGlobs and Filespec in rust

[tobni]

hyperfine --warmup 1 -n 'main' 'PYENV_VERSION=pants@3.14.3 PANTS_SOURCE=/tmp/pants-main pants --no-pantsd dependencies ::' -n 'add/source-field-in-rust' 'PYENV_VERSION=pants@3.14.3 PANTS_SOURCE=<redacted>/pants pants --no-pantsd dependencies ::'
Benchmark 1: main
  Time (mean ± σ):     32.467 s ±  0.416 s    [User: 37.098 s, System: 11.984 s]
  Range (min … max):   31.933 s … 33.181 s    10 runs
 
Benchmark 2: add/source-field-in-rust
  Time (mean ± σ):     30.605 s ±  0.456 s    [User: 35.140 s, System: 11.875 s]
  Range (min … max):   30.097 s … 31.519 s    10 runs
 
Summary
  add/source-field-in-rust ran
    1.06 ± 0.02 times faster than main

[tobni]

Passed tuples to something expecting strings. Pyo3 validation of types catches it.

[tobni]

memoizing these may be design overkill, but userland could suffer if their plugin reads globs in python and we copy to python heap every access.

[tobni]

This is a stylistic choice by me to make rust-coding nicer at the cost of... Something? I dont see why it should be a mutable type (dict /w lists), and the primary consumer seems to be us in FilespecMatcher - not Filespec.

I made a __getitem__ and __eq__ that ~pretends it is still a dict, increasing likelihood of backwards compat.