vim: Fix escape key switching back to default mode instead of normal mode (#31843)

Closes #31728

This PR introduced new setting `"helix_mode"`. Enabling which will
enable the `vim_mode` along with `helix` behavior.

This solves issue where `vim`'s `default_mode` was being used to switch
between mode instead of opening in `default_mode`.

When `helix_mode` is enabled switcing to `Normal mode` will now switch
to `HelixNormal`


Release Notes:

- Fixed - escape key not switching to normal mode when default_mode is
insert
- Added - `helix_mode` setting to enable/disable helix key bindings

---------

Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim_mode_setting/src/vim_mode_setting.rs

@@ -1,7 +1,7 @@
-//! Contains the [`VimModeSetting`] used to enable/disable Vim mode.
+//! Contains the [`VimModeSetting`] and [`HelixModeSetting`] used to enable/disable Vim and Helix modes.
 //!
 //! This is in its own crate as we want other crates to be able to enable or
-//! disable Vim mode without having to depend on the `vim` crate in its
+//! disable Vim/Helix modes without having to depend on the `vim` crate in its
 //! entirety.
 
 use anyhow::Result;
@@ -11,6 +11,7 @@ use settings::{Settings, SettingsSources};
 /// Initializes the `vim_mode_setting` crate.
 pub fn init(cx: &mut App) {
     VimModeSetting::register(cx);
+    HelixModeSetting::register(cx);
 }
 
 /// Whether or not to enable Vim mode.
@@ -38,3 +39,29 @@ impl Settings for VimModeSetting {
         // TODO: could possibly check if any of the `vim.<foo>` keys are set?
     }
 }
+
+/// Whether or not to enable Helix mode.
+///
+/// Default: false
+pub struct HelixModeSetting(pub bool);
+
+impl Settings for HelixModeSetting {
+    const KEY: Option<&'static str> = Some("helix_mode");
+
+    type FileContent = Option<bool>;
+
+    fn load(sources: SettingsSources<Self::FileContent>, _: &mut App) -> Result<Self> {
+        Ok(Self(
+            sources
+                .user
+                .or(sources.server)
+                .copied()
+                .flatten()
+                .unwrap_or(sources.default.ok_or_else(Self::missing_default)?),
+        ))
+    }
+
+    fn import_from_vscode(_vscode: &settings::VsCodeSettings, _current: &mut Self::FileContent) {
+        // TODO: could possibly check if any of the `helix.<foo>` keys are set?
+    }
+}