* add RecyclableMemoryStream dependency and MemoryStreamManager
* organize BinaryReader/BinaryWriter extensions
* add StreamExtensions to reduce need for BinaryWriter
* simple replacments of MemoryStream with RecyclableMemoryStream
* add write ReadOnlySequence<byte> support to IVirtualMemoryManager
* avoid 0-length array creation
* rework IpcMessage and related types to greatly reduce memory allocation by using RecylableMemoryStream, keeping streams around longer, avoiding their creation when possible, and avoiding creation of BinaryReader and BinaryWriter when possible
* reduce LINQ-induced memory allocations with custom methods to query KPriorityQueue
* use RecyclableMemoryStream in StreamUtils, and use StreamUtils in EmbeddedResources
* add constants for nanosecond/millisecond conversions
* code formatting
* XML doc adjustments
* fix: StreamExtension.WriteByte not writing non-zero values for lengths <= 16
* XML Doc improvements. Implement StreamExtensions.WriteByte() block writes for large-enough count values.
* add copyless path for StreamExtension.Write(ReadOnlySpan<int>)
* add default implementation of IVirtualMemoryManager.Write(ulong, ReadOnlySequence<byte>); remove previous explicit implementations
* code style fixes
* remove LINQ completely from KScheduler/KPriorityQueue by implementing a custom struct-based enumerator
* hle: Some cleanup
This PR cleaned up a bit the HLE folder and the VirtualFileSystem one, since we use LibHac, we can use some class of it directly instead of duplicate things. The "Content" of VFS folder is removed since it should be handled in the NCM service directly.
A larger cleanup should be done later since there is still be duplicated code here and there.
* Fix Headless.SDL2
* Addresses gdkchan feedback
