This PR aims to let the user pair Marina with a cosigner and then "allow" to spend some funds via another injected provider.

New Domain: Account

• An Account is an interface. The idea is to map serializable data stored in reducers to Accounts.
• The wallet reducer now stores the account data. Each account is identified by an AccountID.
• encrypted mnemonic and all the main data used to restore the Main Marina wallet represents the mainAccount.
• this "mainAccount" is the single sig account used to own a "regular" asset.
• the user data (utxos, txs etc...) is the mixed balances of all accounts set up in Marina Wallet, same for coin selection, blinding, and signing.

Restricted Asset account

• The user can pair with a cosigner using Settings > Cosigner > Add Cosigner screen.
• Pairing with a cosigner will add a new account to Marina wallet reducer: RestrictedAssetAccount.
• This account is a 2of2 account working with the Cosigner interface.
• the user can generates multisig addresses via "Receive" page (:warning: WIP: need to hardcode the assets (with logo and tickers) in select asset screen, now it's a "restricted asset" btn (useful for testing in regtest)).

"Allowance" provider

the coinos provider is injected via inject-script.ts. Its implementation is described in coinosBroker file. It let's to getCoins --> returns the utxos owned by the 2of2 Marina account and allowCoin --> create a SIGHASH_NONE tx and send it to Cosigner (via Cosigner.allow method).

mocked cosigner
This PR uses a mocked cosigner for testing purposes as a Cosigner interface.

TODO:
This PR is the first base block for the restricted assets but need some task to be fully complete:

• "real" cosigner implementation.
• handle the list of restricted assets.
• Handle allowed coins in Marina ???
• Only inject the coinos provider on specific hostnames ??

@tiero please review