SG-40373: Alt+Shift key up doesn't clear Alt modifier (#879) (#880)

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### Summarize your change.
This update includes Alt in handling that already exists for clearing
modifiers after a modifier mismatch occurs.

### Describe the reason for the change.
`Alt` + `Shift` modifier key-down was incorrectly identifying as `Meta`
+ `Shift` on key-up. As a result, `Alt` state continued after key up,
which caused operators to think RV was hung -- spacebar wouldn't
play/pause, dragging cursor on screen wouldn't scrub timeline, etc.

### Describe what you have tested and on which operating system.
Reproduced Alt+Shift issue on Linux RHEL 9.4 and RHEL 7.2, using:
* Latest OpenRV main branch
* RV 2023.0.3
* RV 7.2.6

Confirmed it did not happen on MacOS Sequoia.

### Add a list of changes, and note any that might need special
attention during the review.

### If possible, provide screenshots.

Signed-off-by: Will Wira <[email protected]>
Signed-off-by: pbergeron-adsk <[email protected]>
Co-authored-by: pbergeron-adsk <[email protected]>

Author: williamwira

src/lib/app/RvCommon/QTTranslator.cpp

@@ -133,7 +133,10 @@ namespace Rv
                 //  is that in many cases this code causes the control modifier
                 //  to be lost.
                 //
-                if (m_modifiers & Qt::ControlModifier || m_modifiers & Qt::MetaModifier)
+                // Alt modifier included in handling, as a mismatch can
+                // occur when pressing Alt + Shift. Qt can incorrectly
+                // substitute Meta button for Alt on key up.
+                if (m_modifiers & Qt::ControlModifier || m_modifiers & Qt::AltModifier || m_modifiers & Qt::MetaModifier)
                 {
                     m_modifiers = inputEvent->modifiers() & 0xffff0000;
                 }