DOC: Add redirect for moved classes
The new redirects in this commit are for Resampler and Styler

Refactor how we do redirects. Moved all the logic into the
config file, where you state the methods / classes to be redirected.
Removed all the logic from the template, and just look up in the
new html_context variable.

Closes https://github.com/pandas-dev/pandas/issues/16186

Running a test locally ATM.