Refactor signer state machine

[dlachaume]

Content

This PR includes an update of the state machine of the signer in order to prepare the phase of the decentralization of the signature orchestration.

States modifications:

• Signed state is removed
• ReadyToSign and RegisterNotAbleToSign states are added

Transitions:

• Unregistered -> RegisteredNotAbleToSign when registration succeeds but the signer can not sign the current epoch
• Unregistered -> ReadyToSign when registration succeeds and the signer can sign the current epoch
• ReadyToSign -> ReadyToSign when trying to create a new message if any and sign it

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • CHANGELOG file is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • No clippy warnings in the CI
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested
• Documentation
  • Update README file (if relevant)
  • Update documentation website (if relevant)
  • Add dev blog post (if relevant)

Issue(s)

Closes #1922

[github-actions]

Test Results

    4 files  ±0     53 suites  ±0   9m 40s ⏱️ -1s
1 261 tests +9  1 261 ✅ +9  0 💤 ±0  0 ❌ ±0 
1 472 runs  +9  1 472 ✅ +9  0 💤 ±0  0 ❌ ±0 

Results for commit a8a3b5e. ± Comparison against base commit 9fd9ae8.

This pull request removes 9 and adds 18 tests. Note that renamed tests count towards both.

mithril-signer ‑ runtime::runner::tests::test_can_i_sign
mithril-signer ‑ runtime::state_machine::tests::registered_to_registered
mithril-signer ‑ runtime::state_machine::tests::registered_to_signed
mithril-signer ‑ runtime::state_machine::tests::registered_to_unregistered
mithril-signer ‑ runtime::state_machine::tests::signed_to_registered
mithril-signer ‑ runtime::state_machine::tests::signed_to_signed_no_pending_certificate
mithril-signer ‑ runtime::state_machine::tests::signed_to_signed_unsigned_pending_certificate
mithril-signer ‑ runtime::state_machine::tests::signed_to_unregistered
mithril-signer ‑ runtime::state_machine::tests::unregistered_to_registered

mithril-signer ‑ runtime::runner::tests::can_sign_current_epoch_returns_false_when_cannot_get_protocol_initializer_for_current_epoch
mithril-signer ‑ runtime::runner::tests::can_sign_current_epoch_returns_false_when_epoch_service_returns_false
mithril-signer ‑ runtime::runner::tests::can_sign_current_epoch_returns_true_when_epoch_service_returns_true
mithril-signer ‑ runtime::runner::tests::can_sign_current_epoch_when_epoch_service_returns_error
mithril-signer ‑ runtime::runner::tests::can_sign_signed_entity_type_when_signed_entity_type_is_locked
mithril-signer ‑ runtime::runner::tests::can_sign_signed_entity_type_when_signed_entity_type_is_not_locked
mithril-signer ‑ runtime::state_machine::tests::ready_to_sign_to_ready_to_sign_when_can_sign_the_first_signed_entity_type
mithril-signer ‑ runtime::state_machine::tests::ready_to_sign_to_ready_to_sign_when_different_state_than_previous_one
mithril-signer ‑ runtime::state_machine::tests::ready_to_sign_to_ready_to_sign_when_different_state_than_previous_return_state_with_same_epoch
mithril-signer ‑ runtime::state_machine::tests::ready_to_sign_to_ready_to_sign_when_same_signed_entity_type
…

♻️ This comment has been updated with latest results.

[jpraynaud]

Overall looks good 👍

I left few comments and suggestions below.

[jpraynaud]

LGTM 👍