Changes:

• Change the MBS builders into setuptools plugins so now you can now create your own builder plugin
• Updated some documentation
• mbs-build local now builds only from yaml files (this bypasses the need for SCM)
• Only complete the module build when all components are tagged and a KojiRepoRegen message is received
• Don't trigger init handler when importing a local build and mark the build as done after import
• Validate component git refs when a commit is explicitly stated in the modulemd before starting the module build
• Set Access-Control-Allow-Origin to "*" on GET API routes
• Fix duplicate module build state traces
• Make the module build log name configurable