Reduce compiletest code for easier decoupling

[adpaco-aws]

Description of changes:

Refactors the compiletest tool to remove most code not used in this project while still keeping its major features (suite testing, caching, concurrency). This allows us to decouple from the compiler anytime in the future.

For comparison, this is the cloc output on src/tools/compiletest (branch main):

      16 text files.
      16 unique files.                              
       0 files ignored.

github.com/AlDanial/cloc v 1.82  T=0.03 s (515.1 files/s, 271922.2 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Rust                            15           1041            797           6583
TOML                             1              3              0             23
-------------------------------------------------------------------------------
SUM:                            16           1044            797           6606
-------------------------------------------------------------------------------

The output including the changes in this PR:

       9 text files.
       9 unique files.                              
       0 files ignored.

github.com/AlDanial/cloc v 1.82  T=0.01 s (695.0 files/s, 136687.7 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Rust                             8            205            217           1322
TOML                             1              3              0             23
-------------------------------------------------------------------------------
SUM:                             9            208            217           1345
-------------------------------------------------------------------------------

So about 78% (1345/6606) of the code has been remove.

Note that option parsing has been changed to make all arguments optional so the tool still works when called from x.py. Most code there will be removed at the time of decoupling.

Noticed that #289 is not an issue anymore (probably due to other changes in rmc.py). Removed the code to disable related checks and reference to the issue.

Resolved issues:

Resolves #289

Call-outs:

Testing:

• How is this change tested? Running existing regression.

• Is this a refactor change? Yes.

Checklist

• Each commit message has a non-empty body, explaining why the change was made
• Methods or procedures are documented
• Regression or unit tests are included, or existing tests cover the modified code
• My PR is restricted to a single feature or bugfix

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.

[celinval]

That's awesome! I would prefer if we copy the heavily modified compiletest to a different location and keep the current one as is. I'm worried that this may make the next upstream synchronization much harder.

[adpaco-aws]

Copied the original proposal into src/tools/rmctest and replaced the path to compiletest in bootstrap. Unfortunately, the copyright check is failing to pass - do we add it or override?

[adpaco-aws]

Went back to the original proposal. Added "modifications" copyright notices for each file.

[celinval]

Looks good to me. Thanks