Setup Git client for Jupyter

What does this MR do?

Sets up the git client in Jupyter installation.

#47138 (closed)

#58815 (moved)

With this other MR we are installing a git extension in our Jupyter installation. This MR does following,

• We request additional scopes (read_repository, write_repository) with Jupyter's oauth login flow. The access_token generated in oauth login is available as environment variable in Jupyter.
• We create ~/.git-credentials file (with gitlab username and access_token) so that the git extension can use it by default. User can even drop down to a terminal in Jupyter and perform git clone/commit/push/pull with Gitlab repositories.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team