Implement Helix Support (WIP) (#19175)

Closes #4642 

- Added the ability to switch to helix normal mode, with an additional
helix visual mode.
- <kbd>ctrl</kbd><kbd>h</kbd> from Insert mode goes to Helix Normal
mode. <kbd> i </kbd> and <kbd> a </kbd> to go back.
- Need to find a way to perform the helix normal mode selection with
<kbd> w </kbd>, <kbd>e </kbd>, <kbd> b </kbd> as a first step. Need to
figure out how the mode will interoperate with the VIM mode as the new
additions are in the same crate.

crates/vim/src/object.rs

@@ -143,7 +143,7 @@ impl Vim {
         match self.mode {
             Mode::Normal => self.normal_object(object, cx),
             Mode::Visual | Mode::VisualLine | Mode::VisualBlock => self.visual_object(object, cx),
-            Mode::Insert | Mode::Replace => {
+            Mode::Insert | Mode::Replace | Mode::HelixNormal => {
                 // Shouldn't execute a text object in insert mode. Ignoring
             }
         }