rename _isSecureObjectWhileLockScreenActivated, mark as stable API (#14044)
Follow up of GHSA-rmq3-vvhq-gp32
Summary of the issue:
The function _isSecureObjectWhileLockScreenActivated may be useful to add-on authors.
Therefore the API should become stable, i.e. not prefixed with an underscore.
The function is also not named in a way that makes it clear what a "secure object" is.
Description of user facing changes
None
Description of development approach
Rename _isSecureObjectWhileLockScreenActivated to objectBelowLockScreenAndWindowsIsLocked