chore(kate): Move kate back to "common" as it is cross-platform

- Link Kwrite config with Kate

common/.config/kate/externaltools/gitk.ini

@@ -0,0 +1,12 @@
+[General]
+actionName=externaltool_gitk
+category=Git
+cmdname=gitk
+executable=gitk
+icon=git-gui
+name=gitk
+output=Ignore
+reload=false
+save=None
+trigger=None
+workingDir=%{Document:Path}