Set conflict resolution tool

[joshaber]

Let the user select a conflict resolution tool that we can open for them.

[joshaber]

How do we imagine this working? A dropdown based on git mergetool --tool-help? Name and command text entry? @pmn @donokuda

[joshaber]

Moving this to M3 to match up with "Open Conflict Resolution Tool" button.

[joshaber]

@donokuda @niik This needs some 🏩 👀

[joshaber]

@niik and I talked this over and decided to punt it and #71 to 1.0 when we have time to think more about our conflict resolution story.

[SurajGupta]

I'd like to make another pitch for an external diff tool. I'm looking at the current product roadmap and the upcoming releases seem to tackle some pretty niche problems. One of the most basic scenarios/needs of a version control system is determining what's changed before you commit. It's no offense to this product, but the existing diff-view is just mediocre. Often enough it's actually misleading because it over- or under-emphasizes the extent of the changes to a file. That's no surprise, it's a hard problem and other companies have been focused on this space for over a decade. It's gotten to point now where I don't even look at the diff in GitHub Desktop, I switch to Source Tree so I can quickly perform a UI driven External Diff. I think y'all are underestimating the impact an External Diff feature would have from Day 1 of release versus pretty much everything that's in the product roadmap right now.

[billygriffin]

Thanks for the feedback @SurajGupta! We've been doing a bunch of work so far this year on the merge flow, and the logical conclusion of that is the question, "so you've made it easier to collaborate and merge work, but when there are conflicts Desktop still doesn't handle that well, now what?"

This is something we're actively looking at in #5400, so I'm going to close this issue in favor of that one. We completely agree that a better experience for when conflicts arise has the potential to significantly improve the flow.