Rename Window::ImplIsAccessibleNativeFrame and make it public

The way to determine whether this window is a "native frame"
doesn't look particularly specific to a11y, so rename it
to just `Window::IsNativeFrame` and make it public in order
to reuse it in a follow-up commit.
Also move the implementation out of the source file that
implements accessibility-specific Window methods for
consistency.

Change-Id: I980f251cacce6a601e86fc6261a231b799b30317
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155798
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

0 files changed, 0 insertions, 0 deletions