feat: linkedin v2 provider

[hperl]

This PR adds a new "v2" LinkedIn provider that overwrites the issuer URL which is set to https://www.linkedin.com even though the discovery URL is under https://www.linkedin.com/oauth/.well-known/openid-configuration. The v2 provider uses the generic provider for as much work as possible and only overwrites the concrete issuer URL.

Additionally, I had to "discover" the format of the locale claim, which is an object for LinkedIn and a string for Discord.

The tests "just" test that we can now do a successful discovery.

Additionally, I confirmed this working manually.

Related issue(s)

Fixes #3655

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got the approval (please contact
  security@ory.sh) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further Comments

[codecov]

Codecov Report

Attention: Patch coverage is 90.32258% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 77.96%. Comparing base (49e1a39) to head (21bf198).

Files	Patch %	Lines
selfservice/strategy/oidc/provider_linkedin_v2.go	85.71%	2 Missing ⚠️
selfservice/strategy/oidc/provider_discord.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3804      +/-   ##
==========================================
- Coverage   77.97%   77.96%   -0.01%     
==========================================
  Files         357      358       +1     
  Lines       25138    25166      +28     
==========================================
+ Hits        19601    19621      +20     
- Misses       4031     4036       +5     
- Partials     1506     1509       +3     

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[zepatrik]

Easy fix 👍

[aeneasr]

All tests fail