Restructure remote client crate, consolidate SSH logic (#36967)

This is a pure refactor that consolidates all SSH remoting logic such
that it should be straightforward to add another transport to the
remoting system.

Release Notes:

- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/file_finder/src/file_finder.rs

@@ -1381,7 +1381,7 @@ impl PickerDelegate for FileFinderDelegate {
                         project
                             .worktree_for_id(history_item.project.worktree_id, cx)
                             .is_some()
-                            || ((project.is_local() || project.is_via_ssh())
+                            || ((project.is_local() || project.is_via_remote_server())
                                 && history_item.absolute.is_some())
                     }),
                     self.currently_opened_path.as_ref(),