Implement RFC-007: Passwordless authentication for Git repositories for all providers and controllers

[dipti-pai]

This issue tracks the implementation of RFC-007 : Passwordless authentication for Git repositories

WorkItems

Implement pkg changes

• [ ] Implement azure auth pkg to obtain workload identity credentials to access ADO - https://github.com/fluxcd/pkg/pull/789
• [ ] Implement caching of git credentials to avoid fetching the credentials from provider repeatedly
• [ ] Implement aws auth pkg to obtain sts credentials to access CodeCommit
• [ ] Implement gcp auth pkg to fetch the access token to access CSR
• [ ] Implement github provider to read the provided secret and get the gh app installation token
• [ ] Implement gitlab provider to read the provided secret and get the access token

Controller changes

• [ ] Add .spec.provider to GitRepository API - https://github.com/fluxcd/source-controller/pull/1591
• [ ] Implement source-controller changes to use the provider to authenticate to git - https://github.com/fluxcd/source-controller/pull/1591
• [ ] Implement IAC changes to use the provider to authenticate to git with support for initializing and using the Git Credential cache - https://github.com/fluxcd/image-automation-controller/pull/747
• [ ] Initialize and use Git Credential cache in source controller
• [ ] Initialize and use Git Credential cache in IAC

Integration tests

• [x] Add terraform module for provisioning AzureDevOps project and repository in organization - https://github.com/fluxcd/test-infra/pull/44
• [ ] Add end-to-end test for Azure that provisions the required cloud infrastructure (AKS cluster, workload identity) and Azure DevOps repository and validates cloning a git repository with cloud provider credentials - https://github.com/fluxcd/pkg/pull/793

Code of Conduct

• [X] I agree to follow this project's Code of Conduct

[Jaykul]

When we have issues to "Implement RFC-###" it would be helpful to put the RFC title in the issue title: "Implement RFC-007 Passwordless authentication for Git repositories"

If you want to put something else in, as you did here, we should at least put it in that first line, so instead of "This issue tracks the implementation of RFC-007" ... you'd save most people a click if it said "This issue tracks the implementation of RFC-007 Passwordless authentication for Git repositories"