1359 linkedin auth

[ewan-escience]

Add LinkedIn as OpenID provider for signing in

Changes proposed in this pull request

• Add LinkedIn as OpenID provider for signing in
• Add documentation and fix some typos
• Use status code 303 instead of the default (which happens to be 302) when redirecting after signing in, as it semantically and technically better fits the purpose
• Remove unused functions and environment variables from the auth module

How to test

• Copy the new env variables from .env.example to .env and fill in the missing values
• docker compose down --volumes && docker compose build --parallel && docker compose up
• Sign in with LinkedIn
• Sign in with other providers to see if this still works

Closes #1359

PR Checklist:

• Increase version numbers in docker-compose.yml
• Link to a GitHub issue
• Update documentation
• Tests

[sonarqubecloud]

Quality Gate failed for 'authentication'

Failed conditions
8.5% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate passed for 'rsd-frontend'

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[dmijatovic]

I have tested:

• SURF: it works
• Azure: it works
• ORCID: it works
• LinkedIn: it works
• Local: it works too
• Helmholtz: it fails

I think the credentials I am using for Helmholtz are old/expired and the reason for failure. @cmeessen Can you test Helmholtz login please?

[ewan-escience]

Thanks for testing. For me, Helmholtz still works.