feat(attach): Support `--first` option for `attach` sub-command to let zellij choose the alphabetically first session; resolve#823
fix(attach-first): Fix `--first` option to choose the first created session in the existent sessions
feat(attach): Support `--index` option to choose the session indexed by provided number like -t option of tmux
feat(attach): Support listing active sessions with index when a provided number is not found in the active sessions
feat(attach): Support listing active sessions with index when a provided number is not found in the active sessions
feat: Add anyhow to uniformly treat error types and avoid panics