Hooks - Create a `before_run` hook (akin to `pre_step_instruction` hook)

[Eikix]

We aim to create a DX-friendly testing experience. To achieve that, we'll need to access important moments of the execution process.
Namely, we'd like to have these known test utils: beforeAll, afterAll, beforeEach ( ✅ we have this pre_step_instruction), afterEach

The before_run hook would be the equivalent of beforeAll and similar hooks. It would run at the very beginning of your process (per test function, i.e. per run). It does not need to execute hints (such as mocking etc.) just yet.

The aim of this issue is to invest brain power in proposing a sound strategy to properly hook into this particular step of the execution process.