Refactor MachObjectFile signature blobs

[jtschuster]

Decided to split up #115800 into a refactor PR with no behavioral changes and a separate PR with the behavior changes. Unfortunately this still ended up being pretty large, but much of the diff is moving code or forwarding method calls in a wrapper.

This PR makes the following changes

• Uses classes instead of structs for blobs, with methods to read and write them from/to a file.
• Create IBlob interface as the common "Blob" base.
• Remove MachObjectFile.CodeSignature, and replace its usage with EmbeddedSignatureBlob.
• Create IMachFileAccess to abstract reading and writing to disk. There are classes that implement reading and writing to a Stream or MemoryMappedViewAccessor. This allows the blobs to be easily written to a memory mapped file, or a MemoryStream for hashing.

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[Copilot]

Pull Request Overview

This PR refactors the handling of Mach-O signature blobs by replacing structs with classes and introducing a common IBlob interface, while also consolidating and removing redundant code files. Key changes include:

• Converting blob representations to classes with read/write methods.
• Introducing the IBlob interface and reorganizing blob types.
• Abstracting file access via the new IMachOFileAccess interface.

Reviewed Changes

Copilot reviewed 30 out of 30 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
FileUtils/EndianConversionExtensions.cs	Adds ulong conversion method for consistency.
Enums/HashType.cs	Adds HashTypeExtensions for creating hash algorithms and obtaining hash sizes.
Enums/CodeDirectorySpecialSlot.cs	Updates comment with a reference link.
Enums/BlobMagic.cs	Adjusts ordering of enum members without altering underlying values.
BinaryFormat/SymbolTableLoadCommand.cs	Renames the struct for clarity and adjusts default check accordingly.
BinaryFormat/LinkEditLoadCommand.cs	Renames the struct and updates the constructor and default check.
BinaryFormat/Blobs/SuperBlob.cs	Introduces SuperBlob for managing composite blobs and validates blob offsets.
BinaryFormat/Blobs/SimpleBlob.cs	Implements a simple blob type for binary read/write operations.
BinaryFormat/Blobs/RequirementsBlob.cs	Wraps a SuperBlob to represent an empty Requirements blob.
BinaryFormat/Blobs/EmbeddedSignatureBlob.cs	Implements an EmbeddedSignature blob that aggregates sub-blobs.
BinaryFormat/Blobs/CodeDirectoryBlob.cs	Implements a CodeDirectoryBlob with header parsing and blob writing logic.
BinaryFormat/Blobs/CmsWrapperBlob.cs	Implements a CmsWrapperBlob using a SimpleBlob as inner storage.
BinaryFormat/Blobs/BlobParser.cs	Provides logic to parse a blob based on its magic number.
BinaryFormat/Blobs/BlobIndex.cs	Adds a constant for blob index size.
AppHost/HostWriter.cs	Updates Mach-O file access to use the new IMachOFileAccess interface.

[agocke]

LGTM thanks!

[jtschuster]

I'm going to go ahead and merge. @elinor-fung I'll apply any review feedback to the follow up PR.