feat: Implement Powder Snow

[xRookieFight]

Original work by @Azvyl - ported from pmmp/PocketMine-MP#6857

This pull request adds support for powder snow as a block and item, including its interactions with entities and buckets.

Powder Snow Block and Item Implementation

• Added new PowderSnow block
• Added powder snow bucket as a new item. Includes bucket empty/fill powder snow sounds
• Introduced freezing mechanics for entities: entities accumulate freeze ticks when inside powder snow, which slow movement and eventually cause damage. Entities are protected from freezing if wearing leather armor
• Synced freeze progress ratio to clients for visual effects and added new damage cause for freezing
• Added new sound classes for powder snow bucket interactions

This PR does not implement:

• Damage should not occur if an entity falls onto a carpet placed on powder snow (Magma blocks don't work any more pmmp/PocketMine-MP#2041)
• Powder Snow Cauldron
• Entity attribute modifiers protocol (Slowness Effect levels >= 7 do not reset FOV when removed pmmp/PocketMine-MP#1551)

1.17.0 - Caves & Cliffs

Related issues & PRs

pmmp/PocketMine-MP#5964
pmmp/PocketMine-MP#5163

Changes

API changes

• Added PowderSnow class
• Added SolidBucket class
• Added Living::getFreezeProgressTicks()
• Added Living::setFreezeProgressTicks(int $freezeProgressTicks)
• Added Living::getFreezeProgressRatio()
• Added Living::getFreezeThresholdTicks()
• Added Living::getFreezeProgressState()
• Added Living::setFreezeProgressState(?bool $state)
• Added Living::canFreeze()
• Added EntityDamageEvent::CAUSE_FREEZE

Tests

https://www.youtube.com/watch?v=QVkKMMUlHjE

Plugin:
https://gist.github.com/DavyCraft648/ca56d2587da2b08a983cf3e648e5c0c8