This patch implements panel expansion saving and resetting for property search.
While property search is active, the panel expansion is based on whether
or not it has a search result. When the search finishes, the panel expansion returns
to its state before the search started. However, any panels that were interacted
with during the search won't reset their expansion.

This requires adding a new runtime flag for panels, PANEL_USE_CLOSED_FROM_SEARCH.
It also requires better handling for animation when panel expansion changes with
a PANEL_WAS_CLOSED flag. UI_panel_is_closed gets the search-dependent
expansion stated, but this function is intentionally not used in every single case where
the expansion is accessed-- in some cases it's necessary to use PNL_CLOSED directly.