Aghabeiki has tried to use other extension but it didn't fit, so he created GitDiffer.
I also want to use other diff tools in vscode explorer.
tested on macOS Mojave.
for running difftools, use explorer in vscode, select two or three files, right click and select "Launch Difftool for ..."
for running git difftools, use source control toolbox in vscode, right click on file and select "Launch Difftool for ..."
for running git mergetool, use source control toolbox in vscode, beside the title menu (...), select the "Launch Mergetool" or simple open the command plate and run "Launch Mergetool"
Installation Steps
First install diffmerge or any other alternatives.
Add this configuration to your git global config :