Add getters referendumStatus, referendumInfo for referenda precompile

[4meta5]

Exposes referendum{Status, Info} in precompiles

We have the following enum for ReferendumInfo:

{
	/// Referendum has been submitted and is being voted on.
	Ongoing(
		ReferendumStatus<
			TrackId,
			RuntimeOrigin,
			Moment,
			Call,
			Balance,
			Tally,
			AccountId,
			ScheduleAddress,
		>,
	),
	/// Referendum finished with approval. Submission deposit is held.
	Approved(Moment, Option<Deposit<AccountId, Balance>>, Option<Deposit<AccountId, Balance>>),
	/// Referendum finished with rejection. Submission deposit is held.
	Rejected(Moment, Option<Deposit<AccountId, Balance>>, Option<Deposit<AccountId, Balance>>),
	/// Referendum finished with cancellation. Submission deposit is held.
	Cancelled(Moment, Option<Deposit<AccountId, Balance>>, Option<Deposit<AccountId, Balance>>),
	/// Referendum finished and was never decided. Submission deposit is held.
	TimedOut(Moment, Option<Deposit<AccountId, Balance>>, Option<Deposit<AccountId, Balance>>),
	/// Referendum finished with a kill.
	Killed(Moment),
}

So we expose this by adding a precompile getter for referendumStatus that tells us which variant the enum is. Then we have 3 more getters for each unique variant structure:

• ongoing_referendum_info for ReferendumInfo::Ongoing
• closed_referendum_info for ReferendumInfo::{Approved, Rejected, Cancelled, TimedOut} and returns the ReferendumStatus as well as the inner data
• killed_referendum_block for ReferendumInfo::Killed