Implement actions and triggers!

[Pablete1234]

What are actions? Actions are the next generation of kits. Kits in fact, are a type of action.

Why not just use kits? Kits are always player-scoped, this is not ideal for all features, there's alot of interoperability between kits and actions so this shouldn't be an issue (kits can have player-scoped actions, and kits themselves are a type of player-scoped action), and actions can be scoped-out or scoped-in.

This is mainly a stepping stone towards #881, it is also laying down the ground for #1001, as those will no longer be kits, and will just be actions instead.

Currently the only implemented actions are action (an action with other actions inside), message, switch-scope, and kit

  <kits>
    <kit id="spawn">
      <item slot="0" unbreakable="true" material="stone sword"/>
      <action>
        <message text="You were given a kit!"/>
      </action>
    </kit>
  </kits>
  <actions>
    <action id="do-stuff" scope="player">
      <message text="Sent a chat message!"/>
      <switch-scope outer="player" inner="team">
        <message text="All players on the team are getting this one!"/>
        <switch-scope outer="team" inner="player">
          <kit id="spawn"/>
        </switch-scope>
      </switch-scope>
      <kit>
        <item>diamond</item>
      </kit>
    </action>
    <message id="standalone-text" text="This is a standalone text trigger"/>
    <trigger filter="some-dynamic-filter" action="do-stuff" scope="player"/>
    <trigger filter="another-dynamic-filter" action="standalone-text" scope="player"/>
  </actions>

Update:
triggers have been renamed to actions
when has been renamed to trigger

It makes more sense that "actions" are "triggered" by triggers. The triggers listen for dynamic filters. this was feedback from @Pugzy

[Pablete1234]

Implemented bound inference, so specifying the scope of a trigger isn't required if it can be infered from the parent, the biggest effect is switch-scope only requires inner, as long as the outer can be derived.

Example where it can be infered:

  <actions>
    <actionid="trigger-id" scope="player">
      <switch-scope inner="match">
        <message text="This is match scoped! Converted from player to match"/>
      </switch-scope>
    </action>
  </actions>

Example where it can NOT be inferred (outer is required here, or else it won't work):

  <action>
    <switch-scope id="scope-switch" outer="player" inner="match">
      <message text="This is match scoped! Converted from player to match"/>
    </switch-scope>
    <action id="trigger-id" scope="player">
      <action id="scope-switch"/> <!-- This references the trigger defined above -->
    </action>
  </actions>

Additionally, now the Kit interface fully implements Trigger, because at the end, kits are just a trigger that is scoped to a player. This means you can just define a kit inside a trigger instead of being forced to reference one.

  <action>
    <kit id="a-kit">
      <item>diamond</item>
    </kit>
    <trigger filter="some-filter" action="a-kit" scope="player">
  </action>

In this situation, the trigger is working exactly equally as a <lend kit="a-kit" filter="some-filter"/> would.

Also, Actions now support triggering and untriggering, in the same way removable kits work.