Improve HIPify performance (#14803)

Improve HIPify performance (#14803)

Summary:
```
    Improve performance of pyHIPIFY

    Changes:
    - Pre-compile regexes, don't use regexes when it's not necessary
      (this saves us ~15%)
    - Compile all substitutions for mappings into a single, non-backtracking
      regex using a Trie.  This gives big savings.

    Before, running pyHIPIFY on all files took 15.8s.  Now it takes 3.9s.
```

Stacked on #14769
Pull Request resolved: https://github.com/pytorch/pytorch/pull/14803

Differential Revision: D13342620

Pulled By: ezyang

fbshipit-source-id: 1cfa36b3236bbe24d07080a31cc788a52d740f40