Merge Tool by File Type with Support for UnityYAMLMerge
Currently, there is only support for a single merge tool, which does not cater for different file types. As we work with Unity, for *.asset and *.prefab files Unity provide a UnityYAMLMerge.exe application to perform smart merges. This, of course, doesn't work for merges of code files.
If I follow the Unity docs (https://docs.unity3d.com/Manual/SmartMerge.html) and add their app to the .gitconfig, then GitKraken fails to find any repositories, so I now have to use SourceTree to perform merges when there are conflicts with asset and prefab files, in order to use the tool.
It would be a very useful and powerful feature to keep the `External Merge Tool` as the default choice, but to also allow the definition of file-type / content-type specific merge tools for special circumstances, where alternative tools exist.