Refactor to improve `spec format` speed (#43712)

When looking at where we spend our time in solver setup, I noticed a fair bit of time is spent
in `Spec.format()`, and `Spec.format()` is a pretty old, slow, convoluted method.

This PR does a number of things:
- [x] Consolidate most of what was being done manually with a character loop and several
      regexes into a single regex.
- [x] Precompile regexes where we keep them 
- [x] Remove the `transform=` argument to `Spec.format()` which was only used in one 
      place in the code (modules) to uppercase env var names, but added a lot of complexity
- [x] Avoid escaping and colorizing specs unless necessary
- [x] Refactor a lot of the colorization logic to avoid unnecessary object construction
- [x] Add type hints and remove some spots in the code where we were using nonexistent
      arguments to `format()`.
- [x] Add trivial cases to `__str__` in `VariantMap` and `VersionList` to avoid sorting
- [x] Avoid calling `isinstance()` in the main loop of `Spec.format()`
- [x] Don't bother constructing a `string` representation for the result of `_prev_version`
      as it is only used for comparisons.

In my timings (on all the specs formatted in a solve of `hdf5`), this is over 2.67x faster than the 
original `format()`, and it seems to reduce setup time by around a second (for `hdf5`).

0 files changed, 0 insertions, 0 deletions