Add option for code context menu items to have dynamic width (#37404)

Follow up to https://github.com/zed-industries/zed/pull/30598

This PR introduces the `display_options` field in the
`CompletionResponse`, allowing a code context menu width to be
dynamically dictated based on its larger item. This will allow us to
have the @-mentions and slash commands completion menus in the agent
panel not be bigger than it needs to be. It may also be relevant/useful
in the future for other use cases.

For now, we set all instances of code context menus to use a fixed
width, as defined in the PR linked above, which means this PR shouldn't
cause any visual change.

Release Notes:

- N/A

Co-authored-by: Michael Sloan <mgsloan+github@gmail.com>

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

@@ -15,7 +15,7 @@ use gpui::{
 use language::{Anchor, Buffer, CodeLabel, TextBufferSnapshot, ToOffset};
 use menu::{Confirm, SelectNext, SelectPrevious};
 use project::{
-    Completion, CompletionResponse,
+    Completion, CompletionDisplayOptions, CompletionResponse,
     debugger::session::{CompletionsQuery, OutputToken, Session},
     lsp_store::CompletionDocumentation,
     search_history::{SearchHistory, SearchHistoryCursor},
@@ -685,6 +685,7 @@ impl ConsoleQueryBarCompletionProvider {
 
             Ok(vec![project::CompletionResponse {
                 is_incomplete: completions.len() >= LIMIT,
+                display_options: CompletionDisplayOptions::default(),
                 completions,
             }])
         })
@@ -797,6 +798,7 @@ impl ConsoleQueryBarCompletionProvider {
 
             Ok(vec![project::CompletionResponse {
                 completions,
+                display_options: CompletionDisplayOptions::default(),
                 is_incomplete: false,
             }])
         })