Firestore - Service Account creds + document create with specific id

[adrian-martinez-onestic]

Summary

This PR adds two features:

• Allows to use Google Service Accounts for Firestore nodes authentication.
• Allows to create Firestore documents with specific ids (optionally).

Details

While its possible to use Firestore using a service account, it is currently not supported by n8n, as noted at https://docs.n8n.io/integrations/builtin/credentials/google/#compatible-nodes. Allowing to use a service account in this node allows not depending on a personal account, and provides a reliable way to connect to Firestore.

In this way, proposed changes are backwards compatible, and offer the possibility of using either Oauth2 or Service Account authentication, and optionally, supply a document id, as it is possible while calling API or creating the document manually through the UI:

[CLAassistant]

All committers have signed the CLA.

[netroy]

Since maintainers aren't allowed to edit this PR, I'm unable to fix the CI issues. Can you please cherry-pick this commit, and merge the latest master back in 🙏🏽. Once the CI is green, we can merge.

When creating any future PRs, please make sure that this checkbox is checked

[adrian-martinez-onestic]

Cherry-picked commit with CI fixes, also updated branch with latest master changes

[janober]

Got released with [email protected]