feat(fish): add GitHub Copilot CLI

fish/functions/copilot_what-the-shell.fish

@@ -0,0 +1,15 @@
+function copilot_what-the-shell
+    set TMPFILE (mktemp)
+    trap 'rm -f $TMPFILE' EXIT
+    if github-copilot-cli what-the-shell $argv --shellout $TMPFILE
+        if test -e "$TMPFILE"
+            set FIXED_CMD (cat $TMPFILE)
+            echo -s "$FIXED_CMD"
+            eval "$FIXED_CMD"
+        else
+            echo "Apologies! Extracting command failed"
+        end
+    else
+        return 1
+    end
+end