Commands Rework

[sovdeeth]

Description

The long-awaited command rework! This PR serves as a tracker for work done, and individual command rework PRs should be merged into this branch instead of directly to dev/feature.

Existing work:

Prior to this PR, some work has already been done towards the command rework.

• Pickle put a decent amount of effort into decoupling the existing system from Bukkit, though it is by no means complete.
• Sovde refactored command cooldowns to allow more control and flexibility, and allowing users to access more info about cooldowns.

Work to be done:

This PR is in a draft as details have not yet been hammered out, but the current goals are to provide the following:

• integrated tab complete using a section
• choice arguments that auto-supply tab completions (optional/required literals also auto-supply)
• validation section that allows you to use whatever logic you want as well as ensure x (like asserts) to add on to the default argument parsing restrictions
• subcommands that allow you to use command tree logic
• Full decoupling from Bukkit
  • Possible addition of Brigadier integration
• Full or nearly full back-compatibility with existing commands.

These are not final and are purposely slightly vague, as more discussion needs to occur before deciding on exact courses. This PR will be updated semi-regularly to reflect the current state of affairs. The following is a rough idea of what these goals would look like in a final form, though, again, details and implementation are subject to change. This, too, will be updated semi-regularly.

command /action:
  permission: server.admin

  subcommand (do|delete) <text>:
    tab complete:
      set completions for arg 1 to {fields::*}
    validation:
      ensure {fields::*} contains arg 1 with error "invalid action"
    usage message: "please input an action name"
    trigger:
      if choice 1 is "do":
        do arg 1
      else
        delete arg 1

  subcommand add <action:text>:
    validation:
      ensure {fields::*} doeesn't contain {_action} with error "action already exists"
    trigger:  
      add arg 1 to {fields::*}

  subcommand list:
    trigger:
      send {fields::*}

  default trigger:
    send {fields::*}

Feedback and opinions welcome as comments on this PR, in the skriptlang-development channel on the skUnity discord, or in the SkriptLang testing discord.

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Target Minecraft Versions: any
Requirements: none
Related Issues: #6934, #6560, #4830, #3894, #3642, #3408, #2809, #2155, #1197, closes #3408, closes #2809