Backport #10320: Convert validate.sh to a Haskell script

[mergify]

Closes #10317.

A Haskell script will be easier to maintain and expand than the existing Bash script.

This also adds a --pattern PATTERN option which lets you filter tests across all test suites.

I've kept the new script's behavior as close to the old script's behavior as possible, to reduce design discussion on this PR.

TODO

• Add cabal-validate/README.md to make it obvious where to look for logic and how to interact with the program
• Add Haddock comments to most definitions

Future work

• It should be possible to override the default tasty args (currently --hide-successes)
• --list-steps only lists the steps that are enabled with the given command-line options, not all possible steps; ./validate.sh --list-steps and ./validate.sh --list-steps --run-cli-suite give different results! (This is an existing bug in the old script.)
• Perhaps "steps" should be divided into "suites"; for example, the lib-tests step runs five different test suites, making it take much longer than necessary to reproduce test failures.
• Commands printed to users should be shell escaped. (Exiting bug in the old script.)
• --help output could use some love; it wasn't very clear to me what various commands do.
• --keep-going mode to ignore failures and continue executing tests/suites.
• The output is really verbose, because the command lines are so long.

  ---

  This is an automatic backport of pull request Convert validate.sh to a Haskell script #10320 done by Mergify.

[mergify]

Cherry-pick of 582a5c7 has failed:

On branch mergify/bp/3.12/pr-10320
Your branch is up to date with 'origin/3.12'.

You are currently cherry-picking commit 582a5c747.
  (fix conflicts and run "git cherry-pick --continue")
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  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   Makefile
	new file:   cabal-validate/cabal-validate.cabal
	new file:   cabal-validate/main/Main.hs
	modified:   project-cabal/pkgs/tests.config

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   validate.sh

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally