terminal/search: Partially fix search in terminal.

There are two issues with search in terminal as is:
- terminal's pane is not registered as a "legit" pane, so we dispatch buffer search bar::Deploy on the most recent "legit" pane. By legit I mean that
  workspace::active_pane will *never* return terminal pane as active.
- We've had the implementation of as_searchable commented out. Duh!

This commit fixes second issue. That means that if you drag the terminal over to the main editor pane (so that it's in a "legit" pane), it'll work. 1st issue still stands though.

crates/terminal_view/src/terminal_view.rs

@@ -28,7 +28,7 @@ use workspace::{
     item::{BreadcrumbText, Item, ItemEvent},
     notifications::NotifyResultExt,
     register_deserializable_item,
-    searchable::{SearchEvent, SearchOptions, SearchableItem},
+    searchable::{SearchEvent, SearchOptions, SearchableItem, SearchableItemHandle},
     CloseActiveItem, NewCenterTerminal, Pane, ToolbarItemLocation, Workspace, WorkspaceId,
 };
 
@@ -714,10 +714,9 @@ impl Item for TerminalView {
         false
     }
 
-    // todo!(search)
-    // fn as_searchable(&self, handle: &View<Self>) -> Option<Box<dyn SearchableItemHandle>> {
-    //     Some(Box::new(handle.clone()))
-    // }
+    fn as_searchable(&self, handle: &View<Self>) -> Option<Box<dyn SearchableItemHandle>> {
+        Some(Box::new(handle.clone()))
+    }
 
     fn breadcrumb_location(&self) -> ToolbarItemLocation {
         ToolbarItemLocation::PrimaryLeft