Refactor AICI to use WebAssembly Component Model

This is a significant change to the AICI Runtime (host) and AICI Controller
(guest) to use WASI components. As part of this change, a significant amount of
unsafe code is removed and the protocol is simplified to remove the need for
"BLOB" types and side-channels.

The protocol is documented in `wit/controller.wit`, and a minimal WASI runtime
is provided to AI CI controllers.

Some notes:
* The AICI runtime now longer directly reads and writes to the guest's memory.
  Instead, the guest provides a `Runner` resource (using WebAssembly Component
  terminology), which exposes the low-level protocol to the host as a
  constructor and trait with methods.
* The Blob protocols are removed entirely, replaced by the `Runner` resource.
  This and other side-channels for communicating with the runtime, e.g. allowed
  tokens (logit biases) outside of `MidProcessResult`, are removed.
* The (Variable) Storage and Tokenizer protocols are separate WebAssembly
  Components, which can be versioned independently of the runtime.
* Types are changed to be consistent with the WebAssembly interface, e.g.:
  `SeqId` is used in far more places to avoid casts.

.devcontainer/Dockerfile-prod-vllm

@@ -2,7 +2,7 @@ FROM rust:1.75.0-bookworm AS aicirt
 
 WORKDIR /workspace
 
-RUN rustup target add wasm32-wasi
+RUN rustup target add wasm32-wasip2
 RUN curl -fsSL https://deb.nodesource.com/setup_18.x | bash -
 RUN apt-get install -y nodejs
 

.devcontainer/common.dockerfile

@@ -31,7 +31,7 @@ ENV RUSTUP_HOME=/usr/local/rustup \
 
 RUN curl https://sh.rustup.rs -sSf | sh -s -- \
      -y --no-modify-path --profile minimal --default-toolchain $RUST_VERSION
-RUN rustup target add wasm32-wasi
+RUN rustup target add wasm32-wasip2
 RUN rustup component add rustfmt
 
 # run as root please; note that settings in devcontainer.json are also needed...

.github/workflows/aicirt-release.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v3
         with:
           submodules: true
-      - run: rustup target add wasm32-wasi
+      - run: rustup target add wasm32-wasip2
       - uses: hendrikmuhs/[email protected]
       - uses: Swatinem/rust-cache@v2
         with:

.github/workflows/aicirt.yml

@@ -18,7 +18,7 @@ jobs:
     - uses: actions/checkout@v3
       with:
         submodules: true
-    - run: rustup target add wasm32-wasi
+    - run: rustup target add wasm32-wasip2
     - uses: hendrikmuhs/[email protected]
     - uses: Swatinem/rust-cache@v2
       with: