fix: update some build permissions when the source repo is private

[leafty]

wip

Closes #1347.

Updated permissions when the source repository is private:

API Endpoint	db.py method	Description	Required Permission
GET /builds/<build_id>	get_build()	Get a single build item	Project Read
GET /environments/<environment_id>/builds	get_environment_builds()	List the build history for a launcher	Project Read
POST /environments/<environment_id>/builds	start_build()	Rebuild (build a new image for the launcher)	Project Write + Repo Read
PATCH /builds/<build_id>	update_build()	Cancel a build	Project Write
GET /builds/<build_id>/logs	get_build_logs()	Get a build's logs	Project Write + Repo Read
-	_refresh_build()	Refresh build status	Project Read (checked before calling)

Note: in the case of POST /environments/<environment_id>/builds, this avoids starting a build which would fail at the source step.