debugger: Add horizontal scroll bars to variable list, memory view, and breakpoint list (#41594)

Closes #40360

This PR added heuristics to determine what variable/breakpoint list
entry has the longest width when rendered. I added this in so the
uniform list would correctly determine which item has the longest width
and use that to calculate the scrollbar size.

The heuristic can be off if a non-mono space font is used in the UI; in
most cases, it's more than accurate enough though.

Release Notes:

- debugger: Add horizontal scroll bars to variable list, memory view,
and breakpoint list

---------

Co-authored-by: MrSubidubi <dev@bahn.sh>

crates/gpui/src/elements/uniform_list.rs

@@ -251,6 +251,8 @@ impl Element for UniformList {
         None
     }
 
+    // self.max_found_width = 0.0
+    //
     fn request_layout(
         &mut self,
         global_id: Option<&GlobalElementId>,