Support for Google JSON object in addition to Keyfile

[MarkKropf]

Currently there is two different methods of providing a filename into the Google provider. To enable support for environments with .env files or container platforms that only support envvars, it would be nice to allow a JSON object with the google auth to be provided.

[paulpopus]

How would this work exactly, allow a string that I parse into an object? Or are you referring to a different thing?