feat: add the HTTP bindings to perform HTTP requests from workers

[Angelmmiguel]

Define the new bindings to perform HTTP request from inside the workers. The outcome of this PR is that workers can import a send-http-request function to send HTTP requests through the host. This features opens many new possibilities and it's a pretty standard API in any worker-based platform.

It refs #165

Interface definition

For now, we are not using the latest WIT syntax (including package). The wit-bindgen version that supports it only works with components. Wasm Workers Server doesn't support components yet, but we will switch to them in the future, while keeping compatibility with core components.

For this reason, we're pinning the wit-bindgen dependency to the v2.0 version on the client side (I'll send a separate PR with these changes).

On the host side, we're using the wit-bindgen-backport fork from the Fermyon team. This fork is compatible with the latest Wasmtime version and the wit-bindgen v2 version.

Changes

• Add the .wit files that defines the bindings and types
• Add a new folder structure in the worker crate for future bindings
• Implement the bindings on Wasm Workers Server using reqwest

[ereslibre]

LGTM! Thanks @Angelmmiguel. Some comments :)