Bump LKG and package.json to 5.0.0-dev.20230112

[jakebailey]

• Updates package.json/node_modules to 5.0.0-dev.20230112 with an override to force its usage (even though it's a major version bump).
• Bumps LKG to this nightly to get Preserve alias symbols on references to type aliases via imports #51152, Fix inferences between alias type arguments and defaulted alias type arguments #51771, Improve logic that chooses co- vs. contra-variant inferences #52123, Tweak co/contra inference logic from #52123  #52180 for use in Enable strictFunctionTypes #49929.
• Adds a script (hereby bump-lkg-to-nightly) which automates bumping package.json and LKG in lockstep, until we eventually drop LKG on main.

This PR looks huge because #51699 effectively completely rewrote tsserver.js.

[DanielRosenwasser]

🤷🏻‍♂️

[jakebailey]

I bisected just to be sure what happened. It was #51152 that broke #49929, and then #51762 fixed it, which is confusing as I thought that was just a crash fix.

[jakebailey]

So, maybe I just wait for #51771 to be merged before doing this.

[jakebailey]

I've modified this PR to instead bump package.json to the latest nightly + an override to make our dev tooling accept TS 5.0, followed by:

$ rm -rf lib && cp -r ./node_modules/typescript/lib . && git restore ./lib/.gitattributes

Which does basically the same thing that I used to do with git checkout v4.8.4 -- lib but for a nightly build.

This has the benefit of keeping everything in sync and letting tsbuildinfo not break every time LKG changes (since it encodes a bad version from main), at the cost of not being auto-updated for patches since that would be very noisy.

I'm curious what people's opinion is of that (it's in the same spirit as my git checkout-ing, so, I kinda like it, but I also feel like we could totally forego LKG altogether).

[jakebailey]

Thinking about this again, the main benefit is being able to use the new inference features in #49929 without breaking ts-eslint, since without bumping node_modules, it will use 4.9 and not have the new inference features.

[jakebailey]

I've added a task which automates installing a new version of the nightly into package.json/node_modules and copying it to LKG:

$ hereby bump-lkg-to-nightly
Using ~/work/TypeScript/Herebyfile.mjs to run bump-lkg-to-nightly
Starting bump-lkg-to-nightly
> npm install --save-dev --save-exact typescript@next

up to date, audited 353 packages in 626ms

found 0 vulnerabilities
Finished bump-lkg-to-nightly in 922ms
Completed bump-lkg-to-nightly in 922ms

We can of course update this out of band when needed, but to bring them back in sync again, this task can be used.

Eventually per #52199 we'll drop lib entirely, in which case this won't be needed anymore.

[jakebailey]

I'll redo this PR tomorrow once #51771 is in.

[jakebailey]

This PR should be ready for review; all needed PRs are merged in main and released in nightly.

[jakebailey]

This hardcodes @next, but feasibly we may want (after 5.0 release) to switch to a stable build. But, I suspect that by then, we'll have deleted LKG anyway.

[weswigham]

Presumably we keep manually bumping the LKG in main for now?

[jakebailey]

Yes, when required for one reason or another.

[jakebailey]

But, this won't be updated in the nightly package-lock update, since they'd get out of sync, and keeping them in sync so will create loads of churn (the antithesis of what we're hoping to get out of this ordeal).

[weswigham]

Presumably we keep manually bumping the LKG in main for now?