Searchbar in toolbar large screen.

On large screen (desktop/tablet), display the searchbar inside the
toolbar.

The SearchViewManager is altered to treat focus on the "docked"
searchbar the same as expanding the iconified searchbar.

Bug: 391232269
Flag: com.android.documentsui.flags.use_material3
Test: Manual testing && atest DocumentsUIGoogleTests:com.android.documentsui.SearchViewUiTest

Change-Id: I1b5e5ca974fd3cf2bfbe80f2f1bcf4ed4a04d201