Remove wasm-bindgen target

[mikevoronov]

At the moment, AquaVM could be compiled for both marine and wasm-bindgen targets, the first is used server-side and the second on clients. After marine-web 1st stage release, AquaVM could be compiled only to the marine target for both these targets. But wasm-bindgen target could be useful for debugging purposes, since marine-web is not so well tested, and so now it's better to keep both targets and delete wasm-bingen when marine-web become mature.