Allow root origin to force transition phases

[Szegoo]

Closes: paritytech/polkadot-sdk#432

Introduces three new extrinsics that can be used by force origin to transition between phases and rounds:

• force_rotate_round
• force_start_phase - Accepts a phase that we want to transition into as an argument. Only works when transitioning to the Signed or Emergency phase, otherwise fails. Stores the phase we want to transition into in the ForcePhase storage value. The transition will happen at the start of the next block.

Polkadot companion: paritytech/polkadot#6822

[stale]

Hey, is anyone still working on this? Due to the inactivity this issue has been automatically marked as stale. It will be closed if no further activity occurs. Thank you for your contributions.

[Szegoo]

@Ank4n Could you please review this?

[Ank4n]

Could we reuse code either by

• extracting in a separate fn start_signed()
• adding the check for force phase inside the existing arm

						match current_phase {
				Phase::Off if force_phase == Phase::Signed || remaining <= signed_deadline && remaining > unsigned_deadline => {

[Ank4n]

A good reason to extract logic into functions start_<some>_phase is that we can potentially add it to trait ElectionProvider such that other pallets can tell EPM to force phase as well.

[Szegoo]

@Ank4n @kianenigma Could you please approve if the changes are ok?

[gpestana]

@Szegoo we recently added an integration test crate for staking/EPM and other staking related pallets under frame/election-provider-multi-phase/test-staking-e2e and one of the main goals is to document the different edge cases and behaviour of the pallets as close to production as possible. I wonder if you could add a few e2e tests there for this PS and document them, I think that would be very useful for reviewers and also for posterity.

[Szegoo]

I wonder if you could add a few e2e tests there for this PS and document them, I think that would be very useful for reviewers and also for posterity.

That seems like a good idea, getting to it 👍

[Szegoo]

Integration tests are still WIP.

[Szegoo]

@gpestana I've added two integration tests and made up a scenario for both of them. Please let me know if this seems like something reasonable.

[paritytech-cicd-pr]

The CI pipeline was cancelled due to failure one of the required jobs.
Job name: cargo-check-each-crate
Logs: https://gitlab.parity.io/parity/mirrors/substrate/-/jobs/3412044