refactor: strict types

[Thisen]

Reasoning 💡

Comply with TS strict typing. Very much WIP.

Checklist 🧢

• Documentation - N/A
• Tests - N/A
• Ready to be merged - N/A

Affected issues 🎟

Partially fixes #2709. TypeScript conversion should be done in a new PR, to keep this PR more concise.

[Thisen]

@balazsorban44, I've got good progress, however there are two outstanding issues, where I'm unsure what to do:

• in client-legacy.ts, where some get methods from oauth1Client are being promisfied. I think the intent was to replace the callback, but that's not what happening.
• in src/providers/oauth.ts, this line (export type { OAuthProviderType } from "./oauth-types"), but oauth-types doesn't exist.

[balazsorban44]

1. oauth1Client has a callback-based API, while we want to use a Promise-based one. I don't think there is a graceful way of typing that part, I would just set it anywhere necessary. 🤷
2. that is generated by npm run generate-providers

[codecov-commenter]

Codecov Report

Merging #2802 (72be9a8) into beta (4181988) will increase coverage by 0.11%.
The diff coverage is 15.29%.

@@            Coverage Diff             @@
##             beta    #2802      +/-   ##
==========================================
+ Coverage   13.76%   13.87%   +0.11%     
==========================================
  Files          86       86              
  Lines        1359     1362       +3     
  Branches      375      376       +1     
==========================================
+ Hits          187      189       +2     
- Misses       1163     1164       +1     
  Partials        9        9              

Impacted Files	Coverage Δ
src/core/errors.ts	0.00% <0.00%> (ø)
src/core/index.ts	0.00% <0.00%> (ø)
src/core/lib/cookie.ts	0.00% <0.00%> (ø)
src/core/lib/email/signin.ts	0.00% <ø> (ø)
src/core/lib/oauth/authorization-url.ts	0.00% <0.00%> (ø)
src/core/lib/oauth/callback.ts	0.00% <0.00%> (ø)
src/core/lib/oauth/client-legacy.ts	0.00% <0.00%> (ø)
src/core/lib/oauth/client.ts	0.00% <ø> (ø)
src/core/lib/oauth/pkce-handler.ts	0.00% <0.00%> (ø)
src/core/lib/providers.ts	0.00% <0.00%> (ø)
... and 16 more

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[Thisen]

@balazsorban44, feel free to review. :)

[balazsorban44]

@Thisen could you fix the merge conflicts? I changed a bunch of stuff through #2857 and that PR actually converted the last core files to TS as well, only some providers remain js, feel free to convert them as well

[Thisen]

I will 👍

[Thisen]

@balazsorban44, it's done. I think the converting the providers to TS should be a different PR, this one is already rather large.

[Thisen]

@balazsorban44, since you asked for me to fix the conflicts, when will this be merged?