guessers and tables no longer imported by default under MDAnalysis.topology

[IAlibay]

Related to #4753

Expected behavior

I'm just checking if our changes here are resolving issues with the downstream mdakits, and one thing that still seems to be broken with the API is that folks are relying on doing this:

import MDAnalysis
MDAnalysis.topology.guessers.guess_types(...)

Actual behavior

This isn't possible at the moment because we removed the imports from MDAnalysis.topology.core.

Solution

Just adding the import back in MDAnalysis.topology.core as-is won't work because import MDAnalysis will always give you a deprecation warning, which is just a terrible user experience.

Instead we should just switch all the methods under MDAnalysis.topology.guessers to use the deprecate decorator.