Add initial vim mode mode switching

Co-authored-by: Nathan Sobo <nathan@zed.dev>

crates/vim/src/insert.rs

@@ -0,0 +1,28 @@
+use editor::Bias;
+use gpui::{action, keymap::Binding, MutableAppContext, ViewContext};
+use language::SelectionGoal;
+use workspace::Workspace;
+
+use crate::{editor_utils::VimEditorExt, mode::Mode, SwitchMode, VimState};
+
+action!(NormalBefore);
+
+pub fn init(cx: &mut MutableAppContext) {
+    let context = Some("Editor && vim_mode == insert");
+    cx.add_bindings(vec![
+        Binding::new("escape", NormalBefore, context),
+        Binding::new("ctrl-c", NormalBefore, context),
+    ]);
+
+    cx.add_action(normal_before);
+}
+
+fn normal_before(_: &mut Workspace, _: &NormalBefore, cx: &mut ViewContext<Workspace>) {
+    VimState::switch_mode(&SwitchMode(Mode::Normal), cx);
+    VimState::update_active_editor(cx, |editor, cx| {
+        editor.adjusted_move_cursors(cx, |map, mut cursor, _| {
+            *cursor.column_mut() = cursor.column().saturating_sub(1);
+            (map.clip_point(cursor, Bias::Left), SelectionGoal::None)
+        });
+    });
+}