QKeySequence::keyBindings() for StandardKey(SaveAs) do not return any key sequences

Summary:

`QKeySequence::keyBindings()` returns a `QList<QKeySequence>`.
`QKeySequence::StandardKey(63)` returns, correctly, the standard key for 'Save as'.
However, calling:

QKeySequence::keyBindings(QKeySequence::StandardKey(63))

returns an empty QList.

Expected behaviour:
A QList containing something similar to QKeySequence("Ctrl+Shift+S") should be returned.

This works with every other StandardKey that I've tested so far. For example, for the standard 'Save' key, a QList containing QKeySequence("Ctrl+S") is returned.

Background:

In MuseScore, using Qt, we handle common shortcuts using QKeySequence::StandardKey. This is to provide correct cross-platform implementations without us ourselves having to worry about it too much.

Multiple testers report this bug, on Windows and Linux, building with different Qt versions.