GCP wrapper

[aroundthecode]

Add a GCP wrapper to work on Google SQL instances

In reference to #82 and #63 I tried to provide an initial GCP implementation.

To have operator work with GCP you have

1. use postgres connection in secret
2. manually create a Master role e.g. "devops-operators" (must NOT be the same as the connection secret)
3. use such role in database CR e.g. spec.masterRole: devops-operator

DropRole method will check for db owner and will skip master role dropping.

I'm not a GO developer so I tried to keep all modification in gcp.go, please modify at will to make it compliant with other code style

Working with both Database and Role CR, both in creation and deletion.
@hitman99

[hitman99]

Thank you for your contribution, I will get this reviewed today

[aroundthecode]

Updated as requested

[aroundthecode]

@hitman99 any chance you can review this shortly and generate a new version?
I'm using a patched operator version, but I'd prefer to stay on the mainstream :)

[hitman99]

@aroundthecode PR approved and merged. Thanks for using my operator :)