[Parent] wasm support for wallet

[alxiong]

This is the parent tracking issue for all tasks related to making CAPE's wallet runnable inside WASM (and browser).

Here are some dependencies we need to work on (basically directly from cape/wallet/Cargo.toml):

espresso libraries

• jellyfish (Initial WASM Support jellyfish#254)
• jf-cap (@alxiong 🚧 this also requires code refactor to catch up jellyfish's recent updates)
• tagged-base64 (https://github.com/EspressoSystems/tagged-base64/pull/51）
• address_book
• cap-rust-sandbox
• commit
• eqs
• espresso-macros
• net
• reef
• relayer
• seahorse

other dependencies

• async-std
• async-traits
• escargot
• ethers (relevant PR here)
• pipe (should we remove this unmaintained dep?)
• shellexpand (try to remove it?)
• structopt
• tempdir (should remove this archived dep. potentially replace with tempfile)
• tide and tide-websockets
• toml (related issue, likely won't support no_std)