Compare benchmarks

### Prerequisites

- [x] I have written a descriptive issue title
- [x] I have searched existing issues to ensure the feature has not already been requested

### 🚀 Feature Proposal

Given this PR in the main repo:

- https://github.com/fastify/fastify/pull/6322

We should:

1. move those workflows to this repository where we checkout the PR's code and the main code and run the comparison
2. in the main repo: when the label is added, we should trigger the workflow added here
3. when the workflow added here ends the execution, it should submit the report back to the caller in the main repository (for sure we will need to add some perf check here)

### Motivation

_No response_

### Example

_No response_