Option to specify wasm-toolchain

[grod220]

Some repos require the use of nightly to be able to build wasm binaries.

This PR introduces a new input var that allows consumers to specify the toolchain for that CI/CD job. The ergonomics are a bit different than the others given it requires two steps: 1) installing the right toolchain and 2) installing a target.

[joncinque]

Do they actually require nightly? I just tried compiling the interface and program crates with the stable toolchain, and it worked fine

[joncinque]

Ah --all-features, screwed over by frozen-abi again

[grod220]

Ah --all-features, screwed over by frozen-abi again

Yes, that's it indeed 😢

[joncinque]

Very slick! Just the bit about calling make build-wasm...

[grod220]

Also, think it would be helpful to make a push a git tag after this. I noticed a few repos depending on @main which may cause us pain down the line if we want to make a breaking change.

[joncinque]

Looks great! And feel free to push a tag if you want, but I'd only use it in downstream repos if necessary.

This repo is for internal consumption, so we don't need to prioritize stability at the cost of development speed by forcing repos to individually upgrade all the time.

[grod220]

True, that's fair. Helpful context 👍