Developing Typescript with VSCode is currently frustratingly slow:

• Opening files in another one of Kibana's 24 independant typescript projects sometimes takes > 60s "initializing TS language features"
• cmd+clicking references within some projects takes > 60s (in my experience test seems to be the slowest)
• Not all type errors show up under VSCode's "problems"
• Running a complete typecheck takes > 60s which slows down the development cycle when doing large type refactors

I believe using [typescript references](https://www.typescriptlang.org/docs/handbook/project-references.html and incremental builds we should be able to make the build time much faster, have type errors show up without having to run scripts/type_check and improve type lookups and navigation in VSCode.

The first iteration #72280

Steps

• src/test_utils to TS project Introduce TS incremental builds & move src/test_utils to TS project  #76082
• src/core to TS project Extract src/core in a separate TS project #76785
• src/plugins/kibana_utils to TS project Add TS projects for src/plugins & x-pack/plugins #78440
• x-pack/plugins/licensing to TS project Add TS projects for src/plugins & x-pack/plugins #78440
• document migration path for other plugins Document ts project references setup #78586
• create a tool to identify plugin deps Create tool to identify plugin import dependencies to support TS project references migration #79343
• plugins migrate to TS project refs. meta issue [Meta] Migrate Kibana plugins to TS project references #80508