ci: manually callable workflow to build .wasm binaries using cosmwasm/rust-optimizer

[Unique-Divine]

Desired Dev X

Suppose that my machine doesn't have the right architecture to generate Wasm bytecode intended for production. This could be Windows without WSL or a Darwin (MacOS) architecture that could result in nondeterminism.

As a workaround, there should be an easy way me to:

1. Push Rust code for contracts that I'm certain will compile to a branch
2. Start a pull request for that branch with the changes
3. Manually trigger or request a repo owner to trigger a workflow that generates the Wasm bytecode (for production) and then publishes it as an artifact for that branch

Then, I can download the artifacts and checksums to include in the pull request.

[Unique-Divine]

• Completed by ci: add GHA workflow to build and release artifacts #107