Add TTL Table support to automatically reclaim data with given retention policy and garbage collect granularity.

[sunxiaoguang]

Feature Request

Describe the feature you'd like:
Add TTL Table support to automatically reclaim data with given retention policy and garbage collect granularity.

Describe alternatives you've considered:
Manually reclaiming expired data.

Teachability, Documentation, Adoption, Migration Strategy:
It's pretty straightforward idea and should be understandable by most people, especially for those who have used systems with such capabilities such as Redis.

[SunRunAway]

TTL feature is released with TiDB v6.5: https://docs.pingcap.com/tidb/stable/time-to-live#periodically-delete-expired-data-using-ttl-time-to-live

tracking issue: #39262