Integrate HOPS for lightweight MCMC sampling

[qacwnfq]

Feature description

MCMC sampling is a core technique and HOPS is a lightweight MCMC library that would allow us to sample parameters in high-dimensional spaces.

@hannemann-tamas If the parameter-gradients are available, we can even use gradient-based MCMC walks.

Additional context

No response

Checklist

• [ ] Attached labels, especially loc:: or model:: labels.
• [ ] Linked to project.