✨ Refactor with lexopt

✨ Add optional third position for specifying layout

Add documentation for usage of layout.

Update build target recommendation to avoid deprecation issues.

Restore the reference as it was.

Implement similar 3 optional position logic with if conditionals rather
than match.

feat: suppport switching with only session name (#1)

* feat: suppport switching with only session name

* refactor: only update `cwd` value inside if statement

🎨 Changed name to zellij-switch