Fix linting: finish the conversion to v9 and flat configs, make lint not silently fail and fix a bunch of type errors

[JasonVMo]

Platforms Impacted

• all, changes should be type only in practice

Description of changes

I realized lint runs were going too fast...when I realized it was silently hiding errors. This led to the realization that the switch to v9 and the new flat config went a bit too easily. So this has a series of fixes of note.

• changed to explicitly running eslint in each folder rather than using the just indirection (which was hiding things)
• included the necessary dependencies in the framework/eslint-config-rules package which defines the lint rules for FURN
• updated lint rules to format them correctly
• increased lint strictness by default, then disabled rules we had to
• removed the repo root config which wasn't actually used by eslint
• changed the vscode setting for linting to point to the one that we actually use, now vscode should reflect the correct rules.

After that it was fixing a number of linting issues:

• generally places where we have type Foo it should actually be extending a type defined to be {}. This was the intent but it was a rookie error on my part.
• included handling for null and made the typing more correct in immutable merge.
• fixed a lot of odds and ends, the rules that are explitly turned back on we should look at, particularly the exhaustive-deps one the the PlatformColor references.

Verification

This should be an eng-sys + typing change so builds are the main validation mechanism.