Support join_by of structured arrays (recarray)

**Is your feature request related to a problem? Please describe.**

We have already supported structured arrays (`numpy.recarray`). It would be great if we can support some advanced method of structured arrays, for example `join_by`.

**Describe the solution you'd like**

Implement [`join_by`](https://www.numpy.org/devdocs/user/basics.rec.html#numpy.lib.recfunctions.join_by).

**Describe alternatives you've considered**

Otherwise, we need a `for-loop` to finish some requirements like `join`.

**Additional context**
Add any other context or screenshots about the feature request here.

The issue points to NumPy's recfunctions.join_by API and Mars's existing structured-array support. Start by locating that support and its tests, then compare the expected behavior with NumPy's documentation. Done means join_by works for structured arrays without the proposed for-loop workaround and is covered by relevant tests.

Written by the indexing model from the issue text.