Automatic merge from submit-queue (batch tested with PRs 58317, 58687, 57872, 59063, 59328). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

add number measurement for bound/unbound pv/pvc

**What this PR does / why we need it**:

Implement number measurement for bound/unbound pv/pvc defined in the [Metrics Spec](https://docs.google.com/document/d/1Fh0T60T_y888LsRwC51CQHO75b2IZ3A34ZQS71s_F0g/edit#heading=h.bwzmc2tktae)

ref feature: [ kubernetes/features#496](https://github.com/kubernetes/features/issues/496)

**Release note**:

```release-note
Intended for post-1.9
```