Inspector does not remember its window docked status / position

Context: this applies to all revisions since the Inspector window has been introduced.

Description:
- Window status (docked/undocked), size and position of the F9 palette are restored across MuseScore session: fine.
- Window status, size and position of the Inspector, however, are reset to the default (docked on right app window side) each time MuseScore starts.

Expected: Once the Inspector window is set to a certain status, size and position, these are remembered and restored in next MuseScore sessions.