Report multi select on list boxes that support it (#18409)
Link to issue number:
Closes #18365
Summary of the issue:
NVDA does not report whether multiple selection is supported on a list control.
Description of user facing changes:
NVDA now reports multi select for a list that supports multiple selection.
Description of developer facing changes:
None
Description of development approach:
Add a new MULTISELECTABLE state, analogous to oleacc
Map that state to the oleacc state for MSAA
Map the UIA Selection Can Select Multiple property to the new state.
