migrate to git-mirror to support different revision / module

[asiyani]

This PR contains breaking changes....
CRD now accepts both repoName and repoURL as optional field
Controller in this PR will use repoURL instead of repoName to resolve repository added by admins.

Following steps should be followed to minimise disruption

1. Deploy New Version of CRD only so that we can add repoURL to modules
2. Update ALL modules and add repoURL field keeping old repoName as it is.
3. deploy new version of controller
4. once new version of controller is deployed it will start using repoURL instead of repoName field.
5. we can now remove repoName field from the CRD. as that field will be deleted from next version of CRD