Instead of adding the app templates launched from the backend via
`backend/btrixcloud/templates`, add them to a configmap and mount the
configmap in the same location.
This allows these templates to be updated, like other values in
charts/... without having to rebuild any of the images, speeding up dev
and maintenance time.
Changes include:
- move backend/btrixcloud/templates -> chart/app-templates/
- add app-templates/*.yaml to app-templates configmap
- mount app-templates configmap to /app/btrixcloud/templates/ in api and op containers
