Add ctor from two input iterators to wxArray in STL build too.

This ctor already existed in non-STL build but was omitted from the STL
version.

Closes #15216.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74044 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Add ctor and assign() taking an iterator range to wxVector<>.

Do it for consistency with wxArray and std::vector<>, even if the current
implementation is suboptimal.

See #15216.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74045 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775