Added commands, subcommands, flags, arguments, and custom help menus

[hrszpuk]

Aim

The aim of this pull request is to add commands/subcommands/flags for controlling the rectx program. Commands proceed directly after the program name rectx <command>. Commands are also required in order to access rectx functionality. Subcommands proceed directly after a command rectx <command> [subcommand]. Subcommands are not required as they are not featured on every command. However, for the commands that utilise subcommands they are always required. Flags are additional parameters for commands/subcommands. Finally, arguments are the values used by commands/subcommands to do some action.

Additions

• Create cli.go and moved cli code in there.
• Added commands: new, build, run, config, template.
• Added subcommands for config and template commands.
• Added flags where necessary.
• Added extra cli utility functions such as ShowUsage and PrintSubcommands.
• Added a general help menu for all commands (ShowHelpMenu).
• Added custom specific help menus for each command which explains the subcommands/flags of each command.

Related issues

• 25

[hrszpuk]

Cute little check list:

• [x] Add templateSubcommandArguments
• [x] Add configSubcommandArguments
• [x] Update ShowUsage to accept a custom command
• [x] Handle command parse errors by showing the help menu instead of exiting
• [x] Suggest the user uses --help when an unknown command is used

[hrszpuk]

Really need to fix workflows next