Duplicate Stage - Select Linked CodeFiles

[Dan-Nolan]

We should have some kind of an additional select UI for deciding with CodeFiles are linked when duplicating code stages. Something like:

[ ] Link All Stages?
    [✓] Link contracts/code.sol
    [✓] Link contracts/helper.sol
    [  ] Link test/testCode.js

This way test files don't get linked, which is potentially confusing and can lead to overwriting previous files. #116 will also help with this UI