Implement --skipLibCheck flag in tsbuild

[MarcCelani-at]

Summary:
Many large composite projects rely on skipLibCheck to improve build times.
However, skipLibCheck does introduce some risk that projects miss typescript errors
in new node module versions they install.

This is in response to Issues #45691, #25613, and #41185

This issue is not tagged with Backlog, but I'd request that it be considered anyway. Reason being: is an issue with many duplicates and a long history of discussion. I don't believe that this change should be controversial.

[ ] There is an associated issue in the Backlog milestone (required)
[x] Code is up-to-date with the main branch
[x] You've successfully run gulp runtests locally
[x] There are new or updated unit tests validating the change

Test Plan:
New tsbuild unit test scenario that tests overriding the skipLibCheck value with a command line argument.
Validated with verbose output that the actual build overrode the value in the tsconfig.json file.

Fixes #25613 (partially), #45691, and #41185

[typescript-bot]

The TypeScript team hasn't accepted the linked issue #25613. If you can get it accepted, this PR will have a better chance of being reviewed.

[MarcCelani-at]

Is there any interest in this PR? I'm happy to resolve conflicts if so.

[sandersn]

The hard part of this issue is figuring out the semantics. I'd rather wait on this PR until we've decided on that in the issue discussion. Probably closing it makes the most sense since it's not much code and may well code-rot in the meantime.