[studio] Create Site with Git Repo code quality

[RLChris-Lim]

Code revisions

1. debug logs for happy case for createSitePushToRemote (logger exists for clone, but not push)
2. createSiteCloneRemoteGitRepo and createSitePushToRemote return booleans regarding whether they are successful or not, but method that calls them, createSiteWithRemoteOption doesn't use them, and only returns void. the groovy script doesn't make use of it either, so as long as the createSiteWithRemoteOption returns properly, the response will always be "OK"

[sumerjabri]

Please add debug logs for happy path.
Please add exceptions/flow back to the API to support the exceptions detailed in the spec: http://docs.craftercms.org/en/3.0/developers/projects/studio/api/site/create-site.html

[dejan-brkic]

Done
PR:
craftercms/studio#1012

[RLChris-Lim]

verified change