Rename config_setting

### Description of the feature request:

Sorry for the bike shedding, but the naming of *build settings*, *config settings*, and *constraint settings* makes them unnecessarily difficult to grok.

I suggest renaming `config_setting` to `condition`.

These are not actually "settings" but in fact "conditions". Compare with `//conditions:default`.

### What underlying problem are you trying to solve with this feature?

The general confusion around the three flavors of Bazel "settings."

### Have you found anything relevant by searching the web?

https://groups.google.com/g/bazel-discuss/c/2CNZiC-CvG4/m/EvFshjSUBAAJ

Start by reviewing the `config_setting` concept and the `//conditions:default` reference in the issue, then read the linked bazel-discuss thread for the naming rationale. Determine the scope of the proposed rename across Bazel before deciding what a complete, consistent change would include.

Written by the indexing model from the issue text.