Ability to enable pac for all [new] repos in a GitHub org

Goal

As an admin, I want to configure pac on all Git repositories (existing and also new repos) of a GitHub org so that all teams are onboarded into pac and our golden pipeline that is pre-populated in their git repos runs on every Git change without the teams needing to take any further action.

Rolling out pac across large enterprises with 100s and 1000s of teams is challenging since every single team will need to download `tkn` and `pac` and run `tkn pac create repo`. In these enterprise, teams usually request a project through a self-service portal and a number of Git repositories and namespaces gets created for them. Admin is looking for a way to have pac already setup for these Git repos and namespaces, with a pipeline that they already populate in the Git repos that they create for the teams.

Acceptance Criteria

• Admin can enable GitHub App for all repositories of a GitHub org
• Admin can enable pac to be configured for all repositories of the GitHub org
• Admin can enable pac to be configured for a subset of the repositories of the GitHub org
• Admin can provide a pattern to map the Git repositories to a namespace where the pipelinerun for that Git repo should execute