rewrite double quote strings with many escapes to use ~s

[novaugust]

styler rewriting strings with many escapes involves running regexes against all string literals to detect too many escapes. was worried regexing like that would be too costly but… i think 3/100ths of a second in a repo as large as we have at frame is acceptable?

➜  frameio git:(me/styler-test) hyperfine 'mix format' -i --warmup 1 # with string sigils
Benchmark 1: mix format
  Time (mean ± σ):      3.589 s ±  0.024 s    [User: 16.577 s, System: 1.975 s]
  Range (min … max):    3.556 s …  3.638 s    10 runs

➜  frameio git:(me/styler-test) hyperfine 'mix format' -i --warmup 1 # without string sigils
Benchmark 1: mix format
  Time (mean ± σ):      3.553 s ±  0.027 s    [User: 16.527 s, System: 1.977 s]
  Range (min … max):    3.516 s …  3.602 s    10 runs