[EPIC] Github User Interface

[KevFan]

WHAT

Introduce functionality to interface with Github API in order to add the github user to Orgs / teams etc

The User CR interface might be:

kind: User
metadata:
  - name: kuadra-user
spec:
  awsAccount:
...
...
  github:
    spec:
      organizations:
        - name: kuadrant
          teams:
            - engineering

Things that might be required might include:

• [x] Introduce a GithubUser CR & Controller similiar to AWSAccount
• [ ] Update the Kuadra User CR to include Github User information and create the Github User CR similar to how it's done for AWSAccount
• [ ] Update the GithubUser reconcile to interface with Github API using Github Client in order to add the Github User to the specific org / teams
• [ ] Add integration tests