Sign validator uptime warp msg

[ceyonur]

This pull request introduces several new features and improvements to the warp package, including the addition of a new example application, a no-op state implementation, and enhanced validator state management. The changes also include updates to the backend and verifier components to support the new functionalities.

• Added support for verifying offchain addressed call messages in the verifier_backend (warp/verifier_backend.go). [1] [2]

• Updated imports and added necessary dependencies for the new verification logic (warp/verifier_backend.go, warp/verifier_backend_test.go). [1] [2] [3]

• Added a new example application demonstrating how to request a signature for an uptime message from a locally running node (examples/sign-uptime-message/main.go).

• Updated the backend struct and related functions to include uptimeCalculator, validatorState, and stateLock for improved state management (warp/backend.go). [1] [2] [3]

• Modified backend initialization in tests to include the new state management parameters (warp/backend_test.go). [1] [2] [3] [4] [5]

Validator State Management:

• Implemented a no-op state for validators, providing stub methods for state operations (plugin/evm/validators/interfaces/noop_state.go).

Miscellaneous:

• Updated various test files to accommodate the new state management and verification logic (warp/handlers/signature_request_test.go). [1] [2]
• Removed unused Signable interface from the warp/messages/payload.go file.
• Added comments and minor adjustments to existing code for clarity and consistency (warp/messages/validator_uptime.go).

These changes collectively enhance the functionality and maintainability of the warp package, particularly in terms of state management and message verification.

How this was tested

Added UTs

How is this documented

Not sure if we have any warp types docs.

The base branch was changed.