Create github app for AMT & decisiontree deployment

[anneschuth]

Intro

Currently we use a PAT token to commit from the amt repo to the ai-validation-infra repo that will expire next year. Deploy keys did not work because that can not bypass the branching rules. A quick google recommended using a Github APP to manage the deployment. It needs to be researched if this is possible and then implemented. THe advantage is that we will not have expiring PAT tokens (or when the owner of the PAT token leaves the CD will break)

acceptance criteria

• Use organizational token