Name mode configs foo-mode.properties.

This avoids conflicts if someone, for example, created an editor-mode, and also
paves the way for service properties.

This also fixes some wonkiness in parent resolution.

I also did not do any backward compatibility fiddling. So all zero of you
Scaled users, your mode configs are going to disappear. You can either rename
them to foo-mode.properties manually, or take this opportunity to avail
yourself of the new global config and configure things anew once, to be
inherited by all workspaces. (Then naturally override for any needed workspace
specific niggles.)