Give components their own file type

The name of this issue might be a little narrow but I wanted to make it clear what I am really suggesting, currently component model is dissambiguated from regular wasm modules by a single layer byte in the first 8 bits which works but this makes it deeply integrated with wasm (which is a major point of controversy) and it is basically now just a second bytecode wasm supports which greatly increases the amount of work needed to be done by any tooling that wants to fully support wasm (toolchains like binaryen, runtimes, linkers). I think if we gave components their own identifier (file extension, mimetype, magic number) it would really help as you could either target a wasm component or a module. I think this also helps to re-enforce the idea that components are really a superset of core wasm. Additionally this makes it easier to search through documentation and for consumers to seperate the two layers.

I think this also makes sense once you start looking at wit vs wac where composition is a seperate language to the component type defintions themselves.

The issue names no files, tests, or entry points. Begin by reviewing the component-model design discussion around the existing first-byte distinction and the relationship between WIT and WAC. A complete proposal would need to define a separate component identifier and explain its effects on file extensions, MIME types, magic numbers, and affected toolchains.