Add settings based excludes

[twolfson]

This is related to #9 but not exactly the same. As a personal preference, I like to see node_modules in a project but not search them (unless I have to). I would like to proof of concept a setting (one for each user, project, and language?) that automatically adds exclude paths to the search location.

We should definitely see if we can exclude node_modules yet still search when needed.

The setting name should be disambiguous from 'exclude from Find In directory listing'.