debugger: Make historic snapshot button a dropdown menu (#44307)

This allows users to select any snapshot in the debugger history feature
and go back to the active session snapshot.

We also change variable names to use hsitoric snapshot instead of
history and move the snapshot icon to the back of the debugger top
control strip.


https://github.com/user-attachments/assets/805de8d0-30c1-4719-8af7-2d47e1df1da4

Release Notes:

- N/A

Co-authored-by: Anthony Eid <hello@anthonyeid.me>

crates/debugger_ui/src/session/running/stack_frame_list.rs

@@ -227,7 +227,6 @@ impl StackFrameList {
             }
             this.update_in(cx, |this, window, cx| {
                 this.build_entries(select_first, window, cx);
-                cx.notify();
             })
             .ok();
         })