Feat: add initial Google Drive connector support (#11147)

### What problem does this PR solve?

This feature is primarily ported from the
[Onyx](https://github.com/onyx-dot-app/onyx) project with necessary
modifications. Thanks for such a brilliant project.

Minor: consistently use `google_drive` rather than `google_driver`.

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src="https://github.com/user-attachments/assets/39e792fb-9fbe-4f3d-9b3c-b2265186bc22"
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src="https://github.com/user-attachments/assets/27d70e96-d9c0-42d9-8c89-276919b6d61d"
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### Type of change

- [x] New Feature (non-breaking change which adds functionality)

common/data_source/google_util/constant.py

@@ -0,0 +1,49 @@
+from enum import Enum
+
+from common.data_source.config import DocumentSource
+
+SLIM_BATCH_SIZE = 500
+# NOTE: do not need https://www.googleapis.com/auth/documents.readonly
+# this is counted under `/auth/drive.readonly`
+GOOGLE_SCOPES = {
+    DocumentSource.GOOGLE_DRIVE: [
+        "https://www.googleapis.com/auth/drive.readonly",
+        "https://www.googleapis.com/auth/drive.metadata.readonly",
+        "https://www.googleapis.com/auth/admin.directory.group.readonly",
+        "https://www.googleapis.com/auth/admin.directory.user.readonly",
+    ],
+    DocumentSource.GMAIL: [
+        "https://www.googleapis.com/auth/gmail.readonly",
+        "https://www.googleapis.com/auth/admin.directory.user.readonly",
+        "https://www.googleapis.com/auth/admin.directory.group.readonly",
+    ],
+}
+
+
+# This is the Oauth token
+DB_CREDENTIALS_DICT_TOKEN_KEY = "google_tokens"
+# This is the service account key
+DB_CREDENTIALS_DICT_SERVICE_ACCOUNT_KEY = "google_service_account_key"
+# The email saved for both auth types
+DB_CREDENTIALS_PRIMARY_ADMIN_KEY = "google_primary_admin"
+
+
+# https://developers.google.com/workspace/guides/create-credentials
+# Internally defined authentication method type.
+# The value must be one of "oauth_interactive" or "uploaded"
+# Used to disambiguate whether credentials have already been created via
+# certain methods and what actions we allow users to take
+DB_CREDENTIALS_AUTHENTICATION_METHOD = "authentication_method"
+
+
+class GoogleOAuthAuthenticationMethod(str, Enum):
+    OAUTH_INTERACTIVE = "oauth_interactive"
+    UPLOADED = "uploaded"
+
+
+USER_FIELDS = "nextPageToken, users(primaryEmail)"
+
+
+# Error message substrings
+MISSING_SCOPES_ERROR_STR = "client not authorized for any of the scopes requested"
+SCOPE_INSTRUCTIONS = ""