Allow overriding WASM_BINDGEN_TEST_ADDRESS

[mzyy94]

When running the wasm-pack test in headless mode with WASM_BINDGEN_TEST_ADDRESS environment variable, the default address is set and the URL overriding does not work.

https://github.com/rustwasm/wasm-bindgen/blob/4765448545d7bfc0223fd52f25d966b0bfbf8004/crates/cli/src/bin/wasm-bindgen-test-runner/main.rs#L247-L255

As a result, when the test was run with thses arguments, a different port was assigned than the specified in the WASM_BINDGEN_TEST_ADDRESS environment variable, and the test will not start forever.

$ WASM_BINDGEN_TEST_ADDRESS=http://localhost:3000  wasm-pack test --chrome --headless
[INFO]: 🎯  Checking for the Wasm target...
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.17s
[INFO]: ⬇️  Installing wasm-bindgen...
    Finished `test` profile [unoptimized + debuginfo] target(s) in 0.10s
     Running unittests src/lib.rs (target/wasm32-unknown-unknown/debug/deps/wasm_project-64358ea59372c309.wasm)
Set timeout to 20 seconds...
Running headless tests in Chrome on `http://127.0.0.1:50594/`
Try find `webdriver.json` for configure browser's capabilities:
Ok
Visiting http://localhost:3000/...

To solve this issue, I changed that the WASM_BINDGEN_TEST_ADDRESS environment variable is used when it is set, regardless of the headless mode.

Links:

• Copy port from headless test server when using WASM_BINDGEN_TEST_ADDRESS rustwasm/wasm-bindgen#3873
• Allow overriding headless test URL rustwasm/wasm-bindgen#3861