agent: Support vim-mode in the agent panel's editor (#31915)

Closes #30081

Release Notes:

- Added vim-mode support in the agent panel's editor

---------

Co-authored-by: Ben Kunkle <ben.kunkle@gmail.com>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/src/test/vim_test_context.rs

@@ -1,11 +1,13 @@
 use std::ops::{Deref, DerefMut};
 
 use editor::test::editor_lsp_test_context::EditorLspTestContext;
-use gpui::{Context, Entity, SemanticVersion, UpdateGlobal};
+use gpui::{Context, Entity, SemanticVersion, UpdateGlobal, actions};
 use search::{BufferSearchBar, project_search::ProjectSearchBar};
 
 use crate::{state::Operator, *};
 
+actions!(agent, [Chat]);
+
 pub struct VimTestContext {
     cx: EditorLspTestContext,
 }

crates/vim/src/vim.rs

@@ -433,6 +433,12 @@ impl Vim {
     fn activate(editor: &mut Editor, window: &mut Window, cx: &mut Context<Editor>) {
         let vim = Vim::new(window, cx);
 
+        if !editor.mode().is_full() {
+            vim.update(cx, |vim, _| {
+                vim.mode = Mode::Insert;
+            });
+        }
+
         editor.register_addon(VimAddon {
             entity: vim.clone(),
         });