support passing credentials from memory for google connectors

[rbiseck3]

Description

Google Drive

The existing service account parameter was expanded to support either a file path or a json value to generate the credentials when instantiating the google drive client.

GCS

Google Cloud Storage already supports the value being passed in, from their docstring:

• you may supply a token generated by the
  gcloud
  utility; this is either a python dictionary, the name of a file
  containing the JSON returned by logging in with the gcloud CLI tool,
  or a Credentials object.

I tested this locally:

from gcsfs import GCSFileSystem
import json

with open("/Users/romanisecke/.ssh/google-cloud-unstructured-ingest-test-d4fc30286d9d.json") as json_file:
    json_data = json.load(json_file)
    print(json_data)

    fs = GCSFileSystem(token=json_data)
    print(fs.ls(path="gs://utic-test-ingest-fixtures/"))

['utic-test-ingest-fixtures/ideas-page.html', 'utic-test-ingest-fixtures/nested-1', 'utic-test-ingest-fixtures/nested-2']

[ryannikolaidis]

for clarify maybe just have a separate argument for the path versus the value rather than trying to infer. I think given naming folks are already confused on which we expec

[ryannikolaidis]

yes, gcs does, but we don't expose this as an option in the ingest cli.

ohh so token could be a path OR a value?? got it. yea, I think this is all confusing. also...why is it called a token in one place versus service_key in another?

personally I think we should just be explicit about what we expect having discrete options for path vs value. regardless seems like these should be the same argument name across gcs and google drive (given that we're passing the same key to both...)

per issue description, keep the old options for back compatibility

[ryannikolaidis]

I think in either case we should keep the old key and flag as deprecated (since we have folks actively using these connectors).
let's defer to service_account_key as the one we make common to both, since this is more specific and seems to be more widely referenced in their documents.

[rbiseck3]

What do we use if both are provided? Raise an error?

[ryannikolaidis]

actually, I think google drive is the one folks are really using. so I think fine to not deprecate, but let's just make service_account_key the common one.

[ryannikolaidis]

should also bump the gcs docs page?

[ryannikolaidis]

tested both by passing the value as the argument, and both worked.

after docs bump this is gtg!

[ryannikolaidis]

...per discussion, looks like docs use anonymous, so bumping shouldn't be required for this.

lgtm!