New RestServer Architecture: RestServer -> DB -> ApiServer

By leveraging DB, RestServer can be

1. RAW Consistency
2. High Perf and Powerful Query: List, Paging, Sorting, Summarizing, etc
3. Larger storage quota and duration
4. Active and history jobs are unified and merged together naturally (no need to introduce UID) (https://github.com/microsoft/pai/issues/3935)
5. Job Name can submit idempotently, attach metadata arbitrarily, and query uniquely (https://github.com/microsoft/pai/issues/3935)
6. etc

Features depend on it
List History Jobs: https://github.com/microsoft/pai/issues/3845, https://github.com/microsoft/pai/issues/4610, https://github.com/microsoft/pai/issues/3935
Expose K8s events: part of enrich job debugging info: https://github.com/microsoft/pai/issues/4649

New RestServer Architecture
In short, compared with current architecture, we insert a DB between RestServer and ApiServer.

Sub Tasks

• Database Controller (StatefulSet with initializer, write merger, watcher, poller, gcer)
  • P0 Database schema
  • P0 Database ORM interface in Node.js
  • P0 Service setup (sevice.yaml, start.sh, config, ... , etc)
  • Initializer (handle schema sync, upgrade, legacy, etc...)
    • P0 Version table setup
    • P1 Legacy framework transfer @suiguoxin
  • P0 Write merger
  • P0.5 DB poller
  • API watcher
    • P0 Watcher for framework
    • P2 Watcher for event
    • P2 Watcher for pod
  • #5653
• Rest API Change
  • P0 POST /api/v2/jobs
  • P0 GET /api/v2/jobs
  • P0 GET /api/v2/jobs/{user}~{job}
  • P0 GET /api/v2/jobs/{user}~{job}/config
  • P0 PUT /api/v2/jobs/{user}~{job}/executionType
  • P0 Swagger update
  • P1 /api/v2/jobs/{user}~{job}/job-attempts @suiguoxin #4716
  • P1 /api/v2/jobs/{user}~{job}/job-attempts/{attemptIndex} @suiguoxin
• Webportal
  • P1 paging on list job page
• Fluentd @suiguoxin #4716
  • P1 Fluentd plugin multithread
  • P1 Fluentd change for new schema (for framework history)
  • P2 Fluentd for Pod
• Other
  • P1 Framework controller Decrease GC time?
  • P2 Make postgresql a StatefulSet