Support token sub-types in payments.

[ke6jjj]

Co-authored-by: joecaswell [email protected]

[ke6jjj]

Converting to draft until proper testnet testing is done.

[ke6jjj]

Testing has revealed that wallet_pay_multi isn't working, and what's more, it has probably not worked for a while (if ever).

I think the JSONRPC helper to retrieve list elements under <<"payments">> is returning a singleton tuple containing a list rather than just returning a list.

i.e. this expression

?jsonrpc_get_param(<<"payments">>, Param, false)

is yielding

{ [Payment0, Payment1, ..., PaymentN] }

but the code is expecting

[Payment0, Payment1, ..., PaymentN]

[ke6jjj]

Testing matrix.

Single	Multi	HNT	MOBILE	HST	IOT	No Token	Bad Token	Max	Bones	Return	Result
X			X						X	OK	PASS
X						X			X	OK	PASS
X			X							ERROR	PASS
X			X					X		OK	PASS
	X		X			X			X	OK	PASS
	X						X	X	X	ERROR	PASS
	X		X			X		X	X	ERROR	PASS
	X	X	X						X	OK	PASS
	X			X	X				X	OK	PASS