bulk write after docs was scrolled complete
update default config with migration dispatcher
add bulk parameter idle_timeout_in_seconds, slice_size
clear queue before creating pipeline
check instance available when task state is running
add check_instance_available config for migration dispatcher
get migration task progress info by index_name_unique(index_name+doctype)
get instance list only by gateway
get migration task progress info from es and instance pipeline context
rewrite logic of handling running migration major task
calc complete time in api getDataMigrationTaskOfIndex
init
Co-authored-by: liugq <silenceqi@hotmail.com>