feat(settings): place the search bar at the top or the bottom

Add a search bar position setting and render the bar above the
results or below them, with window insets applied to match.

app/src/main/java/com/example/research/ReSearchApplication.kt

@@ -148,6 +148,7 @@ class ReSearchApplication : Application() {
         val defaultExpansions = SectionExpansionStates(
             isThemeExpanded = false,
             isLanguageExpanded = false,
+            isSearchBarExpanded = false,
             isDictionariesExpanded = true,
         )
         return InitialLaunch(