Bugfixes for hybrid functionals

Description

Bugfixes for hybrid functionals

Fixes a bug for the Coulomb singularity. This was recently introduced and led to a no singularity been computed. The LCAO for orbital dependent functionals is now not computing nor using the xc potential, as the code is not able to compute it. This was causing severe troubles and errors in the case of hybrid functionals, as well as an parallelization dependent result of the LCAO.

A test is also added for covering the Coulomb singularity, to avoid breaking the feature.

News snippet

Bugfixes for hybrid functionals.

Checklist

• I have checked that my code follows the Octopus coding standards
• I have added tests for all the new features added in this request.