Migrate @netlify/config to typescript.

[lukasholzer]

Migrate the packages/config part of the mono repository to typescript as discussed in our internal channels as a low hanging fruit to test how much effort it would be to migrate the whole codebase to typescript.

This is the beginning of a larger effort to enhance the developer ergonomics and velocity inside netlify build.

1. try to make the tooling work with typescript (maybe we have to adapt the testrunner here)
2. Try to keep the PRs rather small by using loose types and allowing a lot of any typing -> just move the files from .js to .ts.
3. after the tooling works with typescript try to enhance the types by hand crafting and adding interfaces and proper function signature types.

[lukasholzer]

Currently blocked by the fact that the tests are not passing on the main branch for me so first need to resolve those issues:

• (edge function tests are failing) https://netlify.slack.com/archives/C023PC3D08J/p1662377365425129
• (missing m1 mac support) https://github.com/netlify/build/pull/4484

[lukasholzer]

Currently blocked by #4495