Poisson solver exercise

[lucaparisi91]

This exercise is a simple implementation of a poisson solver using Jacobi iterations.
This pull request addresses both the cpu implementation and a ported gpu version.
This solves the system of equations ${ \nabla^2_i \phi_i = \rho_i }$ for $i=1,..n$ using the Jacobi method.
This can the usage of

• #pragma omp distribute teams parallel for collapse(2)
• #pragma omp enter data
• custom mappers
• rocm interoperability
• async execution