DEPR: add deprecation warning for com.array_equivalent
xref https://github.com/pandas-dev/pandas/issues/14555

pandas.core.common.array_equivalent was removed without deprecation warning.
This commits adds it back to the core.common namespace with deprecation warning

We should still decide on the usefulness to add to the public API (in this commit I didn't add any pointer to alternative import location)
## [Current coverage](https://codecov.io/gh/pandas-dev/pandas/pull/14567?src=pr) is 85.27% (diff: 100%)

> Merging [#14567](https://codecov.io/gh/pandas-dev/pandas/pull/14567?src=pr) into [master](https://codecov.io/gh/pandas-dev/pandas/branch/master?src=pr) will increase coverage by **<.01%**

``` diff
@@             master     #14567   diff @@
==========================================
  Files           140        140          
  Lines         50689      50693     +4   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
+ Hits          43225      43229     +4   
  Misses         7464       7464          
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last update [1d95179...d5e5173](https://codecov.io/gh/pandas-dev/pandas/compare/1d951794187b72841d59b3dfde0a98309a64dec7...d5e51735853ef58a3514431ad960c9f9c69058ec?src=pr)
 lgtm. I would add a note in the release notes as well.
