Filter out commands before parsing requirements#625

Context: filters Currently it's required to give a complete valid command line in order to be informed the subcommand is not available. This MR makes the filter logic happen before parsing the requirements. Example of the **current unwanted behavior** :point_down: ``` $ cat src/bashly.yml name: cli help: Sample application version: 0.1.0 commands: - name: redis help: Perform actions in redis filters: - redis_running args: - name: id required: true help: ID of something $ ./cli redis missing required argument: ID usage: cli redis ID $ # 😖 I'm required to give a valid command line $ # to be informed this subcommand is not available $ ./cli redis 123 Redis must be running (always fails) ``` I want to be informed the command is invalid earlier, even with an incomplete command. After the change in this MR the behavior is to informe the user the subcommand is not available even if the whole command line is "incomplete": ``` $ ./cli redis Redis must be running (always fails) ```