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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### Type of change

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

common/data_source/google_drive/model.py

@@ -0,0 +1,144 @@
+from enum import Enum
+from typing import Any
+
+from pydantic import BaseModel, ConfigDict, field_serializer, field_validator
+
+from common.data_source.google_util.util_threadpool_concurrency import ThreadSafeDict
+from common.data_source.models import ConnectorCheckpoint, SecondsSinceUnixEpoch
+
+GoogleDriveFileType = dict[str, Any]
+
+
+class GDriveMimeType(str, Enum):
+    DOC = "application/vnd.google-apps.document"
+    SPREADSHEET = "application/vnd.google-apps.spreadsheet"
+    SPREADSHEET_OPEN_FORMAT = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+    SPREADSHEET_MS_EXCEL = "application/vnd.ms-excel"
+    PDF = "application/pdf"
+    WORD_DOC = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
+    PPT = "application/vnd.google-apps.presentation"
+    POWERPOINT = "application/vnd.openxmlformats-officedocument.presentationml.presentation"
+    PLAIN_TEXT = "text/plain"
+    MARKDOWN = "text/markdown"
+
+
+# These correspond to The major stages of retrieval for google drive.
+# The stages for the oauth flow are:
+# get_all_files_for_oauth(),
+# get_all_drive_ids(),
+# get_files_in_shared_drive(),
+# crawl_folders_for_files()
+#
+# The stages for the service account flow are roughly:
+# get_all_user_emails(),
+# get_all_drive_ids(),
+# get_files_in_shared_drive(),
+# Then for each user:
+#   get_files_in_my_drive()
+#   get_files_in_shared_drive()
+#   crawl_folders_for_files()
+class DriveRetrievalStage(str, Enum):
+    START = "start"
+    DONE = "done"
+    # OAuth specific stages
+    OAUTH_FILES = "oauth_files"
+
+    # Service account specific stages
+    USER_EMAILS = "user_emails"
+    MY_DRIVE_FILES = "my_drive_files"
+
+    # Used for both oauth and service account flows
+    DRIVE_IDS = "drive_ids"
+    SHARED_DRIVE_FILES = "shared_drive_files"
+    FOLDER_FILES = "folder_files"
+
+
+class StageCompletion(BaseModel):
+    """
+    Describes the point in the retrieval+indexing process that the
+    connector is at. completed_until is the timestamp of the latest
+    file that has been retrieved or error that has been yielded.
+    Optional fields are used for retrieval stages that need more information
+    for resuming than just the timestamp of the latest file.
+    """
+
+    stage: DriveRetrievalStage
+    completed_until: SecondsSinceUnixEpoch
+    current_folder_or_drive_id: str | None = None
+    next_page_token: str | None = None
+
+    # only used for shared drives
+    processed_drive_ids: set[str] = set()
+
+    def update(
+        self,
+        stage: DriveRetrievalStage,
+        completed_until: SecondsSinceUnixEpoch,
+        current_folder_or_drive_id: str | None = None,
+    ) -> None:
+        self.stage = stage
+        self.completed_until = completed_until
+        self.current_folder_or_drive_id = current_folder_or_drive_id
+
+
+class GoogleDriveCheckpoint(ConnectorCheckpoint):
+    # Checkpoint version of _retrieved_ids
+    retrieved_folder_and_drive_ids: set[str]
+
+    # Describes the point in the retrieval+indexing process that the
+    # checkpoint is at. when this is set to a given stage, the connector
+    # has finished yielding all values from the previous stage.
+    completion_stage: DriveRetrievalStage
+
+    # The latest timestamp of a file that has been retrieved per user email.
+    # StageCompletion is used to track the completion of each stage, but the
+    # timestamp part is not used for folder crawling.
+    completion_map: ThreadSafeDict[str, StageCompletion]
+
+    # all file ids that have been retrieved
+    all_retrieved_file_ids: set[str] = set()
+
+    # cached version of the drive and folder ids to retrieve
+    drive_ids_to_retrieve: list[str] | None = None
+    folder_ids_to_retrieve: list[str] | None = None
+
+    # cached user emails
+    user_emails: list[str] | None = None
+
+    @field_serializer("completion_map")
+    def serialize_completion_map(self, completion_map: ThreadSafeDict[str, StageCompletion], _info: Any) -> dict[str, StageCompletion]:
+        return completion_map._dict
+
+    @field_validator("completion_map", mode="before")
+    def validate_completion_map(cls, v: Any) -> ThreadSafeDict[str, StageCompletion]:
+        assert isinstance(v, dict) or isinstance(v, ThreadSafeDict)
+        return ThreadSafeDict({k: StageCompletion.model_validate(val) for k, val in v.items()})
+
+
+class RetrievedDriveFile(BaseModel):
+    """
+    Describes a file that has been retrieved from google drive.
+    user_email is the email of the user that the file was retrieved
+    by impersonating. If an error worthy of being reported is encountered,
+    error should be set and later propagated as a ConnectorFailure.
+    """
+
+    # The stage at which this file was retrieved
+    completion_stage: DriveRetrievalStage
+
+    # The file that was retrieved
+    drive_file: GoogleDriveFileType
+
+    # The email of the user that the file was retrieved by impersonating
+    user_email: str
+
+    # The id of the parent folder or drive of the file
+    parent_id: str | None = None
+
+    # Any unexpected error that occurred while retrieving the file.
+    # In particular, this is not used for 403/404 errors, which are expected
+    # in the context of impersonating all the users to try to retrieve all
+    # files from all their Drives and Folders.
+    error: Exception | None = None
+
+    model_config = ConfigDict(arbitrary_types_allowed=True)