feat(crypto): CRP-2665 make ic-cdk optional and support wasm+js env in ic-validator-ingress-message

[fspreiss]

Adapts ic-validator-ingress-message to support Javascript WASM environments for Cargo builds via a new feature js, and also makes ic-cdk optional, but still keeps ic-cdk enabled by default, to keep backwards compatibility.

Both

• cargo build -p ic-validator-ingress-message --target=wasm32-unknown-unknown --no-default-features --features=js and
• cargo build -p ic-validator-ingress-message --target=wasm32-unknown-unknown --features=js

succeed.

Note that cargo build -p ic-validator-ingress-message --target=wasm32-unknown-unknown fails because getrandom is not supported for wasm*-unknown-unknown targets. Canisters that want to use ic-validator-ingress-message have to manually fix this, for example by using our ic-crypto-getrandom-for-wasm crate. There is also ic-validator-ingress-message-test-canister to test the usage of ic-validator-ingress-message from a canister.