fix: only show paste hint toast on keyboard copy/cut (#9962)

This differs from the keyboard nav plugin but I think it's correct for an
on-by-default world as it's very weird to encounter this toast on a touch
device with and not helpful for mouse usage (e.g. in MakeCode's context menu).

packages/blockly/core/shortcut_items.ts

@@ -230,7 +230,7 @@ export function registerCopy() {
           ? focused.getRelativeToSurfaceXY()
           : undefined;
       const copied = !!clipboard.copy(focused, copyCoords);
-      if (copied) {
+      if (copied && e instanceof KeyboardEvent) {
         showCopiedHint(workspace);
       }
       return copied;
@@ -284,7 +284,7 @@ export function registerCut() {
         workspace.getAudioManager().play('delete');
         e.preventDefault();
       }
-      if (copyData) {
+      if (copyData && e instanceof KeyboardEvent) {
         showCutHint(workspace);
       }
       return !!copyData;