Rewrite gatsby-link in typescript

[herecydev]

Description

Moves gatsby-link into the typescript world.

Related Issues

Related to #21995

TODO

@blainekasten can you provide some assistance, I have a few things I'm uncertain about:

1. Should the index.d.ts be deleted? As I understand this should now be autogenerated, with the typescript files being the source of truth now.
2. Everything is fairly trivial but the ref/innerRef is causing typescript some problems. There's some real confusion in this definitelytyped thread and the type signature is not easy to go through

3. Should proptypes be in there still? If so, are they to be autogenerated? Or just a carbon copy of typescript props interface?
4. Babel and lint had quite the fight, around L14 you can my efforts to disable eslint to get babel to transpile correctly

Happy to keep working on it but if you have any suggestions let me know

[blainekasten]

why was this change necessary?

[herecydev]

https://eslint.org/docs/rules/no-prototype-builtins

[blainekasten]

1. I think we should leave the index.d.ts for now, I need to look into this more
2. The typings on the ref stuff looks fine. Is there a real problem here? sorry if I'm not following.
3. Leave the proptypes in there. We can look into auto-generating them later if we want, but as a library it still provides value to some people.
4. Shouldn't these just be defined on the window interface you have here?

[herecydev]

Double checking this is an appropriate change. As I understand React doesn't respect any return values (typings also want a void method)

[herecydev]

1. I think we should leave the index.d.ts for now, I need to look into this more
2. Leave the proptypes in there. We can look into auto-generating them later if we want, but as a library it still provides value to some people.

These are both restored, I've got some concerns about what the source of truth is. Proptypes, Typescript and the .d.ts all have a different understanding of the props. I can spend some time trying to converge them better, thoughts?

2. The typings on the ref stuff looks fine. Is there a real problem here? sorry if I'm not following.

Babel will transpile happily but Typescript compiler is not happy. So the PR isn't mergeable until these are fixed

The signature looks something like: type Ref<T> = { bivarianceHack(instance: T | null): void }["bivarianceHack"] | RefObject<T> | null; so I'm not exactly sure how to fix this.

4. Shouldn't these just be defined on the window interface you have here?

This would mean the code has to become window.__BASE_PATH__ and node won't have access to it.

[ascorbic]

We should absolutely aim to move to auto generating the typings. However at the moment we're compiling with Babel, so can't generate them as part of the compilation step. We'd need to either switch to compiling the package with tsc, or run it separately to generate the typings.

[Eyas]

I just saw this PR already attempts this. Sorry for duplicating this work in #22563

Note that I also remove index.d.ts but added a typings generation step to introduce a compatible one. Happy to work on this on either PR

[imjoshin]

Hey! Thanks so much for opening this pull request!

Sadly this PR got stale and didn't have any activity for some time. We're trying to do better with PR reviews! To get a better overview of all actionable PRs we're going through all open PRs and triage them. Since we won't be able to do everything and adding new features always means added maintenance burden, we have to be more picky about what's beneficial for the average user and the project itself longterm.

We think this is a great PR and would love to see it land in Gatsby. We're closing this PR for now but if you're able to rebase onto the latest master branch and try it out with the latest next versions, we'd be happy to review the PR when its re-opened.

We absolutely want to have you as a contributor and are sorry for any inconveniences we caused with replying too late to this PR.

Thanks for submitting to Gatsby! 💜