vim: Support gn command and remap gn to gl (#9982)

Release Notes:

- Resolves #4273

@algora-pbc /claim #4273

This is a work-in-progress. The process for `gn` command is:

- maintain updated vim.workspace_state.search.initial_query
- modify editor.select_next_state with
vim.workspace_state.search.initial_query
- use editor.select_next()
- merge selections
- set editor.select_next_state to previous state

To make this possible, several private members and editor structures are
made public. `gN` is not yet implemented and the cursor still does not
jump to the next selection in the first use.

Maybe there is an better way to do this?

---------

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

crates/vim/Cargo.toml

@@ -39,6 +39,7 @@ ui.workspace = true
 workspace.workspace = true
 zed_actions.workspace = true
 schemars.workspace = true
+util.workspace = true
 
 [dev-dependencies]
 command_palette.workspace = true