WASIX: Map mounted /bin binaries to commands to avoid re-hashing

[theduke]

Commands provided by packages and package dependencies are mapped into the filesystem under /bin/.

These mapped binaries currently have no connection to the underlying command, and are just mounted into the file system as virtual files.
This means each process spawn has to re-compute the hash of the Webassembly code to lod the underlying Module.
Commands already store the hash of the webassembly inside the package, making this step redundant.

This can be quite problematic because hashing of large WASM files is computationally expensive and can take a while.

When spawning many subprocesses, like in typical bash scripts, this will lead to significant overhead.
Even more so in shared environments like cloud servers (Edge).

We should find a way to map the FS-mounted command back to the original BinaryPackageCommand, so the hashed stored there can be re-used.