Initial wasm component support

[elliottt]

This is an initial step towards support for Wasm Components on viceroy 🎉

There are some restrictions to start with:

1. There aren't currently any toolchains that target components directly, and we don't have SDKs that are able to target the fastly:api/compute world that this branch expects
2. Components are not supported for the run command

Additionally, if you run a component with viceroy, you will be greeted with a large warning that indicates that this path is currently unsupported.

Reviewing Advice

For the most part, I tried to keep the modifications to additions, though the files that handle linking and execution of wasm/components did require some modification. The additions in lib/src/component should mostly reflect the current state of the core wasm abi, but componentized via the lib/wit/deps/fastly/compute.wit world.

I would appreciate heavy scrutiny on the following files:

• lib/src/lib.rs
• lib/src/execute.rs
• lib/src/linking.rs

Everything in the lib/src/component tree would definitely benefit from additional eyes, but the plan is to consider that execution path unstable for now, and bugs/changes are expected.

[cee-dub]

🥳

[acw]

OK, most of the comments are either just happy noises, or small suggestions. There were a couple things that I think should be fixed before merge, though. Specifically, there's a wrong implementation in the secret store, and there's an if let ... that should be a match. I also think some guidance on profiling and components might be nice, but I don't think those rise to the level of the first two.

This is awesome stuff!

[acw]

LGTM. Thanks for the changes!