[Feature]: Stacks interface for the block observer

[netrome]

Feature - Stacks interface for the block observer

1. Description

Define a stacks interface for the block observer

1.1 Context & Purpose

To be able to support the block observer event loop, we need to define a stacks interface with the appropriate operations that is needed for the block observer to be able to function.

2.1 Acceptance Criteria:

• We have a trait with the appropriate bounds and methods to support the block observers need to query the Stacks blockchain.