chore: update build for the whole repo

[frontendphil]

What it solves

This PR updates the build for the whole repo.

How this PR fixes it

• All packages produce a CJS and ESM build
• All packages specify their exports according to what bundlers and Node need to understand it
• Tests of different packages do not require the internals of other packages
  • added new package/test-utils entry point where necessary
• The TS setup has been updated to address an OOM error that was caused by the last PR
  • path aliases are specified in the projects that need them instead of inside the global config
  • the baseUrl property is set on the package level, which reduces the memory footprint of a tsc build

What is still open

Some api-kit tests started failing. AFAICT, this has something to do with the PRIVATE_KEY environment variable not being set to the correct value. However, I wonder why this wasn't an issue earlier, and I also can't pinpoint a change I made that would result in this variable not being picked up correctly. I would appreciate help looking into this, as I think I've addressed all other issues.

The build for relay-kit is also a bit weird because the tests in other packages needed to require deeply into this package to mock internals. That's not great, but to "properly" fix this, I think the general test setup needs to be adjusted, and that's definitely out of the scope of what I'm trying to achieve here.

There is also one test in protocol-kit that now times out. But AFAICT it only does that on CI. When I run the tests locally, they all pass.

[frontendphil]

If I'd have read this comment #1043 (comment) 2hrs ago it would have saved me a lot of trouble :D

[dasanra]

@frontendphil Hey thanks for such work. Looks very promising.

Yes don't worry about the remaining CI, secrets are not accessible from forks. We will do a review and bring the code to an integration branch to completely test CI.