class_docstr: This handler handles connection and exectuin of Google BigQuery statements
code: def __init__(self, name, connection_data, **kwargs):
      super().__init__(name)
      self.connection_data = connection_data
      self.client = None
      self.is_connected = False
  
imports: import os
  import json
  from collections import OrderedDict
  from google.cloud import bigquery
  from google.oauth2 import service_account
  from sqlalchemy_bigquery.base import BigQueryDialect
  from mindsdb_sql.parser.ast.base import ASTNode
  from mindsdb_sql.render.sqlalchemy_render import SqlalchemyRender
  from mindsdb.integrations.libs.base import DatabaseHandler
  from mindsdb.integrations.libs.const import HANDLER_CONNECTION_ARG_TYPE
  from mindsdb.integrations.libs.response import HandlerStatusResponse, HandlerResponse, RESPONSE_TYPE
  from mindsdb.utilities import log
label_desc: Use image node_id 1 to create a new BigQueryHandler object from inherited base classes: DatabaseHandler with example: obj = BigQueryHandler(name, connection_data)