Manage CNStore metadata at the CN node. Provide data for CN and HAKeeper's heartbeat process

Approved by: @nnsgmsone, @daviszhen, @reusee, @lni

sql: refactor external table with Process.FileService

init file service on CN and pass to frontend

Co-authored-by: fengttt <fengttt@gmail.com>

* add standalone cn config

* fix typo

* debug log for default

* support mo-service-standalone ci

Co-authored-by: ouyuanning <52741323@qq.com>

cnservice: initialize hakeeper client, txn sender, txn client lazily

Approved by: @zhangxu19830126, @nnsgmsone

cnservice: init hakeeper client

cnservice: init txn sender

cnservice: init txn client

frontend: add wrappedTAETx, wrappedTAEEngine; rename InitDB to InitTAE

frontend: use TxnOperator instead of moengine.Txn

txn: add get txn metadata to txnOperator

replace engine.Snapshot with TxnOperator

Co-authored-by: zhangxu <zhangxu19830126@gmail.com>

1. Connect the cn-service with the frontend and the computation engine.
2. Change the configuraion mechanism to the general method. Remove the auto-generated configuration.

Approved by: @zhangxu19830126, @yingfeng, @fengttt, @aptend, @reusee, @nnsgmsone, @lni