Operational Transaction signed extension.

[kianenigma]

built on top of #3115 and should be updated with it. Should only be marge after #3115 is merged.

• Renames the #[weight] to a more generalized #[meta] tag which can carry static information about both weight, priority and basic functions on top of them. (pub type CallDescriptor = (Weight, TransactionPriority);-- okay name?)
• Consequently refactors some occurrences of weight in the code to the more general structure.

Gist of the change being:

fn validate(
	&self,
	_who: &Self::AccountId,
	info: CallDescriptor,
) -> Result<ValidTransaction, DispatchError> {
	let (weight, priority) = info;
	Self::internal_check_weight(weight)?;
	Ok(ValidTransaction { priority, ..Default::default() })
}

where setting #[meta = WeightedTransaction::Operational()] simply boosts to your priority to infinity and drops your weight to Zero etc.

TODO:

• allow CallMetadata to define will_cause_full_block() to guarantee operational txs will go through.

I will mark this as in-progress now since reviewing it is moot with the additional commits of #3115.

Also closes #3106

[gavofyork]

and drops your weight to Zero etc.

why would it do this? wouldn't that make the transaction free? what stops a dos/sybil attack?

[kianenigma]

This needs to be started over again.