Fix T83020: Transform: AutoConstraint being confirmed without releasing the MMB

The transform modifiers are confirmed by releasing any button.

Thus, the operation can be falsely confirmed if the button that launched
the operation is released after the modifier has been activated.

Previously the events that confirmed the modifiers were hardcoded.

An option to fix this would be to add custom confirmation keyitens for
specific modifiers. But this can be a bit confusing and would make the
modal keymap even bigger.

So the solution here is to skip the button that launched the operation
when confirming the modifier.

source/blender/editors/transform/transform.c

@@ -1203,7 +1203,24 @@ int transformEvent(TransInfo *t, const wmEvent *event)
           handled = true;
         }
         break;
+      case EVENT_NONE:
+      case INBETWEEN_MOUSEMOVE:
+      case INPUTCHANGE:
+      case WINDEACTIVATE:
+      case TIMER:
+      case TIMERJOBS:
+      case TIMERAUTOSAVE:
+      case TIMERREPORT:
+      case TIMERREGION:
+      case TIMERNOTIFIER:
+      case TIMERF:
+        /* Although rare, prevent these events from affecting the state of the modifiers. */
+        break;
       default: {
+        if (event->type == t->launch_event) {
+          /* The user can hold the launch button and release it here. */
+          break;
+        }
         /* Disable modifiers. */
         int modifiers = t->modifiers;
         modifiers &= ~MOD_CONSTRAINT_SELECT;