* Add a test harness to directly execute wasm tests
This commits adds a few new crates and infrastructure to enable comands like:
cargo test --target wasm32-unknown-unknown
The intention here is to make it as low-friction as possible to write wasm tests
and also have them execute in a reasonable amount of time. Eventually this is
also hopefully enough support to do things like headless testing!
For now though this is defintely MVP status rather than fully fleshed out.
There's some more information at `crates/test/README.md` about how it works and
how to use it, but for now this is mainly intended to play around with locally
in this repository for our own tests.
* Port a numbe of `js-sys` tests to the new test framework
This commit ports a number of existing tests for the `js-sys` crate over to the
new test framework created in the previous commit, showing off how they can be
executed as well as drastictlly simplifying the tests themselves! This is
intended to be a proof of concept for now which we can refine over time. This
should also show off that it's possible to incrementally move over to the new
test framework.
