Apply garm credentials via api

[rafalgalaw]

What is the feature you would like to have?

With the upcoming garm release, the github credential section is being removed from the config / migrated to the garm database. Github credentials and endpoints are then only managed via the garm-api. Therefore, the garm-operator needs to expose this as well. See PR #243

Key takeaways whilst interacting with garm-cli of current main branch:

• [github] section in config.toml will be migrated if db table for credentials does not exist on first startup of garm
• There can be multiple endpoints with the same URL => distinguisged by endpoint_name
• For each endpoint, there can be multiple github credential entries

So the operator needs to be able to do the following operations:

1. Create Endpoint:

garm-cli github endpoint create \
    --name mb-github \
    --description "Just an example ghes endpoint" \
    --base-url https://ghes.example.com \
    --upload-url https://upload.ghes.example.com \
    --api-base-url https://api.ghes.example.com \
    --ca-cert-path $HOME/ca-cert.pem

2. Create Credentials for Endpoint as either PAT or GitHub App:

garm-cli github credentials add \
  --name github-creds \
  --description "GitHub PAT for Enterprise" \
  --auth-type pat \
  --pat-oauth-token gh_theRestOfThePAT \
  --endpoint mb-github

garm-cli github credentials add \
  --name github-creds-app \
  --description "Github App with access to repos" \
  --endpoint mb-github \
  --auth-type app \
  --app-id 1 \
  --app-installation-id 99 \
  --private-key-path $HOME/yourAppName.2024-03-01.private-key.pem

3. List and delete endpoints & credentials

garm-cli github endpoint list
garm-cli github credentials list

garm-cli github endpoint delete <NAME>
garm-cli github credentials delete <NAME>

Anything else you would like to add?

No response