[Feature Request]: Allow google readers to take token and credential path

[WAS-PlaiLabs]

Feature Description

The documentation just says to have token.json and credentials.json available, but doesn't specify from where -- and in our instance doesn't work. Is it possible to have paths to supply GoogleDocsReader or it's load_data method?

Credentials.from_authorized_user_file(token_path, SCOPES)
InstalledAppFlow.from_client_secrets_file(creds_path, SCOPES)

Reason

Platform specific filesystems and CDNs

Value of Feature

Allows a more programmatic usage of google reader.