[node] Deposit ERC20

[cf19drofxots]

This adds support for depositing ERC20 tokens into a channel.

Mainly, the API for the deposit method has been extended to include an optional parameter: token address, allowing the operator to specify which ERC20 token they'd like to deposit into the channel.

monorepo/packages/types/src/node.ts

Lines 151 to 156 in 48f820a

	export type DepositParams = {
	multisigAddress: string;
	amount: BigNumber;
	tokenAddress?: string;
	notifyCounterparty?: boolean;
	};

An upcoming PR will add support with withdrawals, and another PR after that to add support for using deposited ERC20 tokens to fund apps.