client: Add wasm support

[Aursen]

Problem

Currently, the anchor client cannot compile or be used in wasm.

Summary of changes

• Reorganization a bit of the client code
• Add wasm dependencies to the client
• Add wasm tests

[vercel]

@Aursen is attempting to deploy a commit to the coral-xyz Team on Vercel.

A member of the Team first needs to authorize it.

[acheroncrypto]

The import error makes sense as we don't have MessageEvent feature enabled here

error[E0432]: unresolved import `web_sys::MessageEvent`
  --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/solana-client-wasm-1.17.2/src/pubsub.rs:10:15
   |
10 | use web_sys::{MessageEvent, WebSocket};
   |               ^^^^^^^^^^^^ no `MessageEvent` in the root

It's still strange that running wasm-pack test --chrome --features pubsub works locally for me even though MessageEvent feature is not enabled.

The errors about str is incorrect because MessageEvent is not enabled, and because the type is not available it doesn't get the correct return type of JsValue::as_string

error[E0277]: the size for values of type `str` cannot be known at compilation time
   --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/solana-client-wasm-1.17.2/src/pubsub.rs:129:75
    |
129 |             if let Some(Ok(notification)) = event.data().as_string().map(|data| {
    |                                                                           ^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `str`
    = note: all function arguments must have a statically known size

Will push a fix for solana-client-wasm.