Helix Select Mode (#37748)

Please credit @eliaperantoni, for the original PR (#34136).
Merge after (#34060) to avoid conflicts.

Closes https://github.com/zed-industries/zed/issues/33838
Closes https://github.com/zed-industries/zed/issues/33906

Release Notes:
- Helix will no longer sometimes fall out into "normal" mode, will
remain in "helix normal" (example: vv)
- Added dedicated "helix select" mode that can be targeted by
keybindings

Known issues:
- [ ] Helix motion, especially surround-add will not properly work in
visual mode, as it won't call `helix_move_cursor`. It is possible
however to respect self.mode in change_selection now.
- [ ] Some operations, such as `Ctrl+A` (increment) or `>` (indent) will
collapse selection also. I haven't found a way to avoid it.

---------

Co-authored-by: fantacell <ghub@giggo.de>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/vim/src/state.rs

@@ -46,6 +46,7 @@ pub enum Mode {
     VisualLine,
     VisualBlock,
     HelixNormal,
+    HelixSelect,
 }
 
 impl Display for Mode {
@@ -58,6 +59,7 @@ impl Display for Mode {
             Mode::VisualLine => write!(f, "VISUAL LINE"),
             Mode::VisualBlock => write!(f, "VISUAL BLOCK"),
             Mode::HelixNormal => write!(f, "HELIX NORMAL"),
+            Mode::HelixSelect => write!(f, "HELIX SELECT"),
         }
     }
 }
@@ -65,7 +67,7 @@ impl Display for Mode {
 impl Mode {
     pub fn is_visual(&self) -> bool {
         match self {
-            Self::Visual | Self::VisualLine | Self::VisualBlock => true,
+            Self::Visual | Self::VisualLine | Self::VisualBlock | Self::HelixSelect => true,
             Self::Normal | Self::Insert | Self::Replace | Self::HelixNormal => false,
         }
     }