#### What type of PR is this?
/kind feature
/area core
/milestone 2.11.x
#### What this PR does / why we need it:
新增用户邮箱验证机制
#### Which issue(s) this PR fixes:
Fixes#4656
#### Special notes for your reviewer:
#### Does this PR introduce a user-facing change?
```release-note
新增用户邮箱验证机制
```
guqing