Improve state applying pattern performance

[SirYwell]

Overview

Description

There are multiple things that can be improved about the state applying pattern:

1. Use BV3#getBlock(Extent) instead of Extent#getBlock(BV3)
2. Avoid costly computeIfAbsent. Not only has that method a very high complexity, but the capturing lambda causes an allocation every time
3. Instead of iterating over the entry set of a map, use an array of specialized entry types

Here is a diff showcasing how this change affects the performance of the applyBlock method when running //set ^[snowy=true] on a selection of 2048x320x2048:

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.