Enhancement: Null coalescing support for HScript

[AbnormalPoof]

Issue Checklist

• I have properly named my enhancement
• I have checked the Issues/Discussions pages to see if my enhancement has already been suggested

What is your suggestion, and why should it be implemented?

Null coalescing is a Haxe language feature that allows you to specify a fallback value if an expression is null. This would greatly improve readability of scripts that access a lot of null-able values.

Example:

// BEFORE
if (characterData != null && type == 'bf') {
	PauseSubState.musicSuffix = (characterData.pauseMusicSuffix != null
		&& characterData.pauseMusicSuffix != '') ? characterData.pauseMusicSuffix : PauseSubState.musicSuffix;
	GameOverSubState.musicSuffix = (characterData.gameOverMusicSuffix != null
		&& characterData.gameOverMusicSuffix != '') ? characterData.gameOverMusicSuffix : GameOverSubState.musicSuffix;
	GameOverSubState.blueBallSuffix = (characterData.blueBallSuffix != null
		&& characterData.blueBallSuffix != '') ? characterData.blueBallSuffix : GameOverSubState.blueBallSuffix;
}

// AFTER
if (type == 'bf') {
	PauseSubState.musicSuffix = characterData?.pauseMusicSuffix ?? PauseSubState.musicSuffix;
	GameOverSubState.musicSuffix = characterData?.gameOverMusicSuffix ?? GameOverSubState.musicSuffix;
	GameOverSubState.blueBallSuffix = characterData?.blueBallSuffix ?? GameOverSubState.blueBallSuffix;
}

[AbnormalPoof]

FYI there's a PR for this (HaxeFoundation/hscript#131) but it's been open for 3-4 months.

[biomseed]

FYI there's a PR for this (HaxeFoundation/hscript#131) but it's been open for 3-4 months.

Funkin Crew has their own fork so they can just merge that in no problem