Transition to eslint

[diksipav]

NOTE: I suggest reviewing commit by commit.

I added the config (eslint.config) for eslint v9 with flat config.

I fixed majority of errors throughout the codebase. And hopefully any types in Remix auth lib.

But definitely a good review is needed of the changes I made.

And there are some errors I wasn't sure about how to fix and also many other any type warnings.

I left todo comments somewhere where I wasn't sure if my "fix" is good enough.

More info: here are ts-eslint
recommended rules,
recommended-type-checked rules,
strict,
strict-type-checked,
stylistic,
stylistic-type-checked.

EDIT:
I removed stylistic "@typescript-eslint/class-literal-property-style" rule because it is enforcing readonly field class literal values, and we use getters in many places (which is actually safer).

TODO:
Check packages/generate/src/syntax/castMaps.ts. Not sure what's this file and how to fix it.

[scotttrinh]

We also want to:

• Remove the extra call to yarn eslint from the test workflow
• Fix the failing errors (I think we can just add an ignore rule for now)
• Remove all of the tslint disable comments throughout