Add a specified set of files

[antspy]

Hi,

I would like to run target determinator based on the set of files in input. Basically I give a bunch of files in input, and target-determinator returns all the targets that depend on those files.

The idea is to implement something like 'test all modified files', where we look at every file in the working tree / staging area (but before any commit) and run all the affected tests.

What do you think?