add boss fight infrastructure

[TheAfroOfDoom]

Summary

This PR adds the underlying functions required for the boss_fight director entity. It currently only supports the first attack phase and the corresponding WARNING sound/visual.

This includes:

• randomized attacks
• fight music
• convenient start functions
• good pipeline for state transitions

The boss fight director essentially functions as a state machine, where we do certain things both during states themselves and during transitions between states.

e.g.:

• transition into attack phase state -> play music, set scores, set tag as boss_fight.phase.attack
• during attack phase state -> attack by picking through a random list depending on phase (phase 0 is x bullets upper/lower, homing vines, friendliness pellets, etc.)
• transition into warn phase state -> play alarm sound, don't start new attacks, set scores, set tag as boss_fight.phase.warn
• during warn phase state -> wait until next state transition (into soul phase)
• etc..

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Reproducing in-game

function _:reset
function _:boss_fight

Preview

This PR's content can only really be shown in a video:

https://youtu.be/PfaDPz_5ew8

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Some cool before visuals though is showing the actual redstone that was originally used to run the boss fight.

redstone	caption
	state handler (attack phase -> soul phase -> ...)
	attack randomizer (color-coded)

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Supplemental changes

• added random attack so we can specify a list of attacks + weights to randomly choose to start
• move objective setup commands to separate file for readability
• add attack entities to entity setup/cleanup function