Implement snappy compression

[AkmalFairuz]

Introduction

Implement snappy compression.

You can change the compression algorithm in the pocketmine.yml file (default: zlib)

network:
  #Compression algorithm. Supported algorithms: snappy, zlib
  compression-algorithm: zlib

An snappy extension is required https://github.com/kjdev/php-ext-snappy that provide snappy_compress and snappy_uncompress function.

You can use this PM php binary fork that has snappy extension https://github.com/AkmalFairuz/php-build-scripts/actions/runs/3106786925 this binary fork is only supported on Linux and MacOS, I need someone to help me to build the PM php binary with snappy extension on Windows

Relevant issues

Changes

API changes

• Added pocketmine\network\mcpe\compression\CompressorPool
• Added public function toNetworkCompressionAlgorithm() : int; in pocketmine\network\mcpe\compression\Compressor interface

Behavioural changes

Backwards compatibility

Follow-up

Tests

[dktapps]

I think we're jumping the gun on this. We're just giving users another way to break their servers without any solid motive to do so.

• Snappy support is still experimental in the game itself.
• There's zero evidence to suggest that this will be beneficial. No performance benchmarks have been done. This is especially important since PM uses libdeflate, which is considerably faster than zlib.
• Snappy does not support compression levels or threshold-based zero compression.
• The mode of operation may also change (I personally suggested per-packet compression type selection, rather than making it global).

[dktapps]

Adding to my previous comments, some specific words about php-ext-snappy:

• This extension doesn't have any support for length limiting on decompressed payloads. This means that the server could be taken down with a zip bomb attack when using Snappy.
• The extension itself isn't supported on Windows, or if it is, there's no instructions how to build it.
• The extension uses antiquated Zend APIs that are harmful to performance.
• It also performs useless copies of the output data, further wasting performance.

[jasonw4331]

The commits in this PR no longer contain a snappy compression implementation