merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/mergetools/codecompare

@@ -0,0 +1,23 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	if $base_present
+	then
+		"$merge_tool_path" -MF="$LOCAL" -TF="$REMOTE" -BF="$BASE" \
+			-RF="$MERGED"
+	else
+		"$merge_tool_path" -MF="$LOCAL" -TF="$REMOTE" \
+			-RF="$MERGED"
+	fi
+}
+
+translate_merge_tool_path() {
+	if merge_mode
+	then
+		echo CodeMerge
+	else
+		echo CodeCompare
+	fi
+}