chore(ci): add compilation cache of main branch

[david-luna]

Which problem is this PR solving?

Improve compilation times by adding a compilation cache which contains the artefacts form the last commit in main. Ref: #3136 (comment)

Short description of the changes

• add a global compilation cache with the cache action https://github.com/actions/cache so its available for all workflow runs
• compilation step restores that cache and uses it for compilation.
• if build happens in main branch (push event) workflow updates the global cache
• on PRs workflow uploads specific cache for test jobs as it was done before

[trentm]

Suggested change

	# Note: we restore the last compilation form main branch
	# so NX will only compile what has changed since then.
	# Cache action is used because can be restores from dfferen workfow runs
	# Restore the nx compilation cache for the latest commit to main.
	# The subsequent 'npm run compile' should only need to compile changed packages.

[trentm]

Do we want to consider not using the cache for pushes to "main"?
IIUC, the way it is now, that compile-cache-main will never start fresh. After a year, it will have a year of possible cruft in it, right? I realize that would mean doing a full clean npm run compile for pushes to main, but we'd still get the benefit of the cache for the more common updates to PRs.