Some ostree builds, like edge, require passing a url to it along with
the ref and parent arguments. This adds an optional --url argument to
the 'composer-cli compose start-ostree' command.
Resolves: rhbz#1929381
This changes the start-ostree command to:
compose start-ostree [--size XXXX] [--parent PARENT] [--ref REF] <BLUEPRINT> <TYPE> [<IMAGE-NAME> <PROFILE.TOML>]
Both of them are optional, and if missing a "" is passed to
osbuild-composer. Also adds more tests for all the various possible
options and removes the provider and profile arguments.
