https://github.com/zed-industries/zed/pull/42837 added the
`cursor_offset_on_selection` field, which displays the cursor *after*
the end of the selection unless a vim visual mode is enabled, in which
case it gets displayed *at* the end of the selection.

However, the real helix is effectively *always* in select mode, and will
always display the cursor at the end of the selection, whether that
selection is made via its visual mode, a movement key, or with the
mouse.

This makes it so that the helix mode setting is taken into account
regardless of the visual-ness of the vim mode in the `sync_vim_settings`
method.

I also considered simply moving `Mode::HelixNormal` up to the `true` arm
of the match in the `is_visual` method since helix is kinda *always* in
visual mode, but I figured that could have some unintended consequences
and chose to err on the side of caution.

Possibly related to #20121

Closes #46998

Release Notes:

- Fixed the cursor offset in non-visual helix selections

Co-authored-by: Nils Koch <mail@nilskch.dev>