Add tendermint-light-client-js crate

[thanethomson]

Closes #463

The vast majority of this PR was taken from #671 with very few changes (thanks @romac for breaking ground there!). I basically added a UI to allow for quick/easy tweaking of the inputs , and will be looking at defining a custom data structure to provide a result back to JavaScript as opposed to serializing Rust's Result type (TBD).

EDIT: I'll leave the verify function parameters and return types as-is for now. We can always look at finding better ways of expressing the types in later versions.

📖 Example README

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
• Wrote tests
• Updated CHANGELOG.md

[webmaster128]

to provide a result back to JavaScript as opposed to serializing Rust's Result type

Result can be used with wasm-bindgen. See https://rustwasm.github.io/docs/wasm-bindgen/reference/types/result.html. I never used it though.

[thanethomson]

Result can be used with wasm-bindgen. See https://rustwasm.github.io/docs/wasm-bindgen/reference/types/result.html. I never used it though.

I'm quite happy to leave it as-is, if that works for you @webmaster128. The result comes through as per the example in the README. It's just a little weird with all the different naming conventions, but it works 😁

[romac]

Looks all good to me! Great job @thanethomson!

The one things we may still want to doo, is add a unit test which calls the exported verify function with some JsValues.

[thanethomson]

The one things we may still want to doo, is add a unit test which calls the exported verify function with some JsValues.

Cool! @romac I've now added two basic tests of the verify method which are now tested in CI too against Chrome and Firefox.

[romac]

Great stuff! Could you also please fix the warnings in light-client-js/src/utils.rs with an #[allow(dead_code)] on set_panic_hook?

[thanethomson]

Great stuff! Could you also please fix the warnings in light-client-js/src/utils.rs with an #[allow(dead_code)] on set_panic_hook?

Done 😁