Refactor selectable table into its own file

* Separate table and mappings, avoid grouping behaviour based on where
it’s being used
* Rename spec to use _ to match file conventions
Split edit_multiple template into partials

* Break into parts for re-use in a modal
* Create an edit multiple modal
* Modify table slightly based on modal local variable passed in
Embolden 'edit selected' button

* Matches styles of other non-input type buttons