Fix tab not working in vi editor mode (#7396)

# Description

The "tab" key now cycles completions in all editor modes, not just
emacs.

# User-Facing Changes

Updated default config

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-utils/src/sample_config/default_config.nu

@@ -447,7 +447,7 @@ let-env config = {
       name: completion_menu
       modifier: none
       keycode: tab
-      mode: emacs # Options: emacs vi_normal vi_insert
+      mode: [emacs vi_normal vi_insert]
       event: {
         until: [
           { send: menu name: completion_menu }