Map d2o d3o when diffthis during a merge conflict like fugitive does

[wodesuck]

Is your feature request related to a problem? Please describe. During a merge conflict, diffthis open a three-way diff, and dp do doesn't work because vim don't known which one to use. Fugitive :Gdiff map d2o d3o to obtain the hunk from "ours" or "theirs" ancestor.

Describe the solution you'd like Map d2o d3o like fugitive.

Additional context Fugitive do this in https://github.com/tpope/vim-fugitive/blob/dd8107cabf5fe85df94d5eedcae52415e543f208/autoload/fugitive.vim#L6515