feat(wasix): Improve module loading performance and API correctness

[theduke]

This commit contains two notable changes:

• The VirtualFile trait is extended with a new as_owned_buffer() method.
  This allows cheap copying of file data if the file is already fully in
  memory, and enables optimisations for code that is aware of this
  functionality by allowing zero-copy cloning.
  This is especially useful for data that is already mmaped.

  The new method has an empty default impl, but is implemented for
  appropriate files (ReadOnlyFile, webc volume files).

• Modifies the Runtime::load_module method to take a new
  HashedModuleData struct

  This has multiple benefits:

  • HashedModuleData is safe by construction, thanks to private fields,
    so the hash it contains will always be valid for the module data.
    This removes a source of bugs due to passing a wrong hash for module
    data to module loaders etc.
  • HashedModuleData can be cheaply creating from a
    BinaryPackageCommand, preventing redundant cloning of data
  • The load_module method now receives owned data that is cheaply
    clonable.
    Previously it received a slice, which introduces the neccessity of
    cloning the data if it needs to be passed on to a different thread.

In combination this PR can significantly reduce memory usage for
high-concurrency scenarios.

Closes #5527

[promptless]

✅ No documentation updates required.

[syrusakbary]

The PR looks good, but we need to do the small change to preserve API compatibility as discussed in Slack

[Copilot]

Pull Request Overview

This PR improves module loading performance and API correctness by introducing a HashedModuleData struct and extending the VirtualFile trait. The changes focus on reducing memory allocations and eliminating the possibility of hash/data mismatches in the module loading pipeline.

• Introduces HashedModuleData struct that safely pairs WebAssembly module data with its hash
• Adds as_owned_buffer() method to VirtualFile trait for zero-copy optimizations
• Deprecates old load_module methods in favor of new load_hashed_module methods

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
lib/wasix/src/runtime/module_cache/hashed_module.rs	New module defining HashedModuleData struct with safe hash/data pairing
lib/wasix/src/runtime/mod.rs	Updates Runtime trait with new hashed module loading methods and deprecates old ones
lib/wasix/src/state/linker.rs	Updates module loading to use HashedModuleData and as_owned_buffer() optimization
lib/wasix/src/bin_factory/mod.rs	Refactors executable loading to use OwnedBuffer and new hashed module APIs
lib/wasix/src/bin_factory/exec.rs	Updates function signatures to accept HashedModuleData instead of byte slices
lib/wasix/src/os/command/builtins/cmd_wasmer.rs	Updates command execution to use new HashedModuleData API
lib/virtual-fs/src/lib.rs	Extends VirtualFile trait with as_owned_buffer() method
lib/virtual-fs/src/mem_fs/file.rs	Implements as_owned_buffer() for memory filesystem files
lib/virtual-fs/src/webc_volume_fs.rs	Implements as_owned_buffer() for webc volume files
lib/package/src/utils.rs	Adds is_container() utility function for container detection
examples/wasi.rs	Updates example to use new HashedModuleData API

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