typespec_client_core: New web_runtime to support wasm32-unknown-unknown

[magodo]

The typespec_client_core::sleep::sleep is using the async_runtime's sleep implementation, which is complicated to support wasm32, and will panic now when targeting to wasm32. Instead of make the standard_runtime to support wasm32 sleep (I wonder if it's feasible), we can instead just introduce another sleep implementation to simply use the gloo_timers::future::sleep.

Also, this PR adds a cfg_attr for conditionally remove the Send trait from the async_trait for the RetryPolicy, as the other parts of the code do.

Fix #2754
Supersedes: #2770

Test

sdk/typespec/typespec_client_core on  wasm_sleep is 📦 v0.6.0 via 🦀 v1.88.0
💤  cargo test -q

running 90 tests
i.................................................................i.................... 87/90
...
test result: ok. 88 passed; 0 failed; 2 ignored; 0 measured; 0 filtered out; finished in 0.84s


running 23 tests
.......................
test result: ok. 23 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 3.27s


sdk/typespec/typespec_client_core on  wasm_sleep is 📦 v0.6.0 via 🦀 v1.88.0 took 4s
💤  cargo test --features=tokio -q

running 91 tests
i.....................................................................i................ 87/91
....
test result: ok. 89 passed; 0 failed; 2 ignored; 0 measured; 0 filtered out; finished in 0.10s


running 23 tests
.......................
test result: ok. 23 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 3.21s


sdk/typespec/typespec_client_core on  wasm_sleep is 📦 v0.6.0 via 🦀 v1.88.0 took 3s
💤  RUSTFLAGS='--cfg getrandom_backend="wasm_js"' wasm-pack test --node --features wasm-bindgen
[INFO]: 🎯  Checking for the Wasm target...
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.14s
[INFO]: ⬇️   Installing wasm-bindgen...
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.11s
     Running unittests src/lib.rs (/home/magodo/github/azure-sdk-for-rust/target/wasm32-unknown-unknown/debug/deps/typespec_client_core-365ee3948d4ee278.wasm)
running 2 tests
test async_runtime::tests::wasm_bindgen_task_execution ... ok
test async_runtime::tests::test_sleep ... ok

test result: ok. 2 passed; 0 failed; 0 ignored; 0 filtered out; finished in 0.17s

Some note about the wasm32 test:

• We can't run the spawned job using futures::executor::block_on(handle), as it introduces a deadlock in browser (since the block_on blocks the current thread)
• The sleep test I can't use Instant::now() when using node as runtime

[github-actions]

Thank you for your contribution @magodo! We will review the pull request and get back to you soon.

[Copilot]

Pull Request Overview

This PR introduces WASM support for typespec_client_core by adding a new web_runtime module that provides a WASM-compatible async runtime implementation. The main goal is to fix the sleep functionality that was previously panicking on wasm32-unknown-unknown targets.

• Adds a new WasmBindgenRuntime implementation using gloo-timers for sleep and wasm-bindgen-futures for task spawning
• Updates the RetryPolicy trait to conditionally remove the Send bound for WASM targets
• Adds comprehensive test coverage for WASM functionality using wasm-bindgen-test

Reviewed Changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
Cargo.toml	Adds workspace dependencies for gloo-timers and wasm-bindgen-futures
sdk/typespec/typespec_client_core/Cargo.toml	Adds optional dependencies and WASM-specific features configuration
sdk/typespec/typespec_client_core/src/async_runtime/mod.rs	Updates runtime creation logic to prioritize WASM runtime when appropriate
sdk/typespec/typespec_client_core/src/async_runtime/web_runtime.rs	Implements new WASM-compatible async runtime using browser APIs
sdk/typespec/typespec_client_core/src/async_runtime/tests.rs	Adds WASM-specific tests and conditional compilation for existing tests
sdk/typespec/typespec_client_core/src/async_runtime/standard_runtime.rs	Updates sleep method signature to use TaskFuture type alias
sdk/typespec/typespec_client_core/src/http/policies/retry/mod.rs	Conditionally removes Send bound from async_trait for WASM compatibility
eng/dict/crates.txt	Adds gloo to the dictionary for spell checking