Support configuring the GitHub OAuth endpoint

[vinokurig]

Signed-off-by: Igor Vinokur ivinokur@redhat.com

What does this PR do?

Currently the GitHub OAuth provider is hardcoded to https://github.com endpoint. In order to support Github Enterprise Server, the endpoint of the GitHub OAuth provider is configurable by the oauth secret.

Screenshot/screencast of this PR

What issues does this PR fix or reference?

fixes eclipse-che/che#21485

How to test this PR?

1. Deploy Che from the custom che-server image built from the PR source: quay.io/ivinokur/che-server:next.
2. Apply the GitHub OAuth secret:

kind: Secret
apiVersion: v1
metadata:
  name: github-oauth-config
  labels:
    app.kubernetes.io/component: oauth-scm-configuration
    app.kubernetes.io/part-of: che.eclipse.org
  annotations:
    che.eclipse.org/oauth-scm-server: github
    che.eclipse.org/scm-server-endpoint: 'http://37.139.177.199/'
data:
  id: YTFmOTcyYWM4ZGM4ZTRlNjJjN2I=
  secret: N2E3OGYwZjIxMmFkOGZlMGEyYjVlZGQzZDlhOTg0NmQxOGVhMDYwYg==
type: Opaque

The secret refers to the GitHub Enterprise Server instace, launched in my local virtualbox environment, and exposed to http://37.139.177.199, see for more details.
3. Ping me to start the GitHub instance :) or use your own application, but configure the endpoint in the secret.
4. Start a factory from http://37.139.177.199/test/test.git or your own repo.

PR Checklist

As the author of this Pull Request I made sure that:

• The Eclipse Contributor Agreement is valid
• Code produced is complete
• Code builds without errors
• Tests are covering the bugfix
• The repository devfile is up to date and works
• Sections What issues does this PR fix or reference and How to test this PR completed
• Relevant user documentation updated
• Relevant contributing documentation updated
• CI/CD changes implemented, documented and communicated

Reviewers

Reviewers, please comment how you tested the PR when approving it.

[vinokurig]

@l0rd @nickboldt Do we need to cherry-pick it to a release branch?

[l0rd]

@vinokurig if that's not too complicated it would be ideal to cherry pick that to 7.52.x branch

[l0rd]

@vinokurig I have added this in the epic for the release of OpenShift Dev Spaces 3.2. Please let me know if you think that it won't be possible to backport it to 7.52.x so that we revert that in time. cc @nickboldt @dmytro-ndp

[vinokurig]

@l0rd Successfully cherry-picked to 7.52.x

[RickJWagner]

@nickboldt Can you please suggest when we might see this commit in Dev Spaces 3.2 or 3.3?
(Reason: We have a customer that can help us validate / provide feedback. Sooner is better.)

[nickboldt]

cherrypicked 7 days ago so built and available from Quay

https://quay.io/repository/devspaces/devspaces-operator-bundle?tab=tags&tag=3.2
https://quay.io/repository/devspaces/iib?tab=tags&tag=3.2