In helix mode, when multiple cursors are active, `,` does not remove the extra cursors

[pedrofgodinho]

Summary

Description

In helix mode, when multiple cursors are active, , should remove all but the active cursor.

Steps to reproduce:

1. Create a file with multiple lines
2. In helix_normal mode, type C (shift + C) to add a new cursor
3. Press ,

Expected Behavior: The first cursor should disappear, and only the cursor on the second line should remain
Actual Behavior: Nothing happens

Zed Version and System Specs

Zed: v0.203.0 (Zed Dev a852bcc)
OS: Windows 10.0.26100
Memory: 31.1 GiB
Architecture: x86_64
GPU: AMD Radeon(TM) Graphics || AMD Corporation || Unknown Driver

[NewtonChutney]

Some helix modes like match mode are half implemented too..
We also miss the menus from helix..