Fix a bunch of other low-hanging style lints (#36498)

- **Fix a bunch of low hanging style lints like unnecessary-return**
- **Fix single worktree violation**
- **And the rest**

Release Notes:

- N/A

crates/assistant_tools/src/assistant_tools.rs

@@ -86,7 +86,7 @@ fn register_web_search_tool(registry: &Entity<LanguageModelRegistry>, cx: &mut A
     let using_zed_provider = registry
         .read(cx)
         .default_model()
-        .map_or(false, |default| default.is_provided_by_zed());
+        .is_some_and(|default| default.is_provided_by_zed());
     if using_zed_provider {
         ToolRegistry::global(cx).register_tool(WebSearchTool);
     } else {

crates/assistant_tools/src/edit_agent/evals.rs

@@ -1586,7 +1586,7 @@ impl EditAgentTest {
         let has_system_prompt = eval
             .conversation
             .first()
-            .map_or(false, |msg| msg.role == Role::System);
+            .is_some_and(|msg| msg.role == Role::System);
         let messages = if has_system_prompt {
             eval.conversation
         } else {

crates/assistant_tools/src/read_file_tool.rs

@@ -201,7 +201,7 @@ impl Tool for ReadFileTool {
                 buffer
                     .file()
                     .as_ref()
-                    .map_or(true, |file| !file.disk_state().exists())
+                    .is_none_or(|file| !file.disk_state().exists())
             })? {
                 anyhow::bail!("{file_path} not found");
             }

crates/assistant_tools/src/terminal_tool.rs

@@ -387,7 +387,7 @@ fn working_dir(
     let project = project.read(cx);
     let cd = &input.cd;
 
-    if cd == "." || cd == "" {
+    if cd == "." || cd.is_empty() {
         // Accept "." or "" as meaning "the one worktree" if we only have one worktree.
         let mut worktrees = project.worktrees(cx);
 
@@ -412,10 +412,8 @@ fn working_dir(
             {
                 return Ok(Some(input_path.into()));
             }
-        } else {
-            if let Some(worktree) = project.worktree_for_root_name(cd, cx) {
-                return Ok(Some(worktree.read(cx).abs_path().to_path_buf()));
-            }
+        } else if let Some(worktree) = project.worktree_for_root_name(cd, cx) {
+            return Ok(Some(worktree.read(cx).abs_path().to_path_buf()));
         }
 
         anyhow::bail!("`cd` directory {cd:?} was not in any of the project's worktrees.");