feat: conflict changes filter

[kpatenio]

Description

Provide an option for extra filtering for the merge conflict explanations on the on-hover popup for the 3 way diff. Options will include:

• refactorings
• moves
• deletes
• additions
• modifications

For refactorings, we can limit to a few types (and probably the most common) for the time being like:

• rename class
• move class
• move method
• move attribute
• extract method

Sample design

Filter button at the top

New window for filter

New changes after deselecting move attribute

Planned setup

Refactorings

Will have to filter the types of refactorings according to what is outputted from RefactoringMiner
See #13.

Additions, deletions, updates, moves

We would have to rely on GumTree or CLDiff for filtering specific modifications. For general changes according to a textual diff, using git4idea should suffice.