[CI] Set up a nightly pipeline to test with dev versions of RAPIDS

[hcho3]

Currently, XGBoost is tested with latest stable version of RAPIDS. As a result, the latest XGBoost may not be fully compatible with an upcoming version of RAPIDS. By the time RAPIDS releases a new version, it may end up packaging a version of XGBoost that's not fully compatible with the new RAPIDS version. See #10175 for an example.

We should set up a CI pipeline that tests XGBoost with development version of RAPIDS on a nightly basis.