Fixes SOC on GPUs

Description

Fixes SOC on GPUs

The kernels were not properly using the complex matrices, leading to wrong results, except when no phases were present.

The code now tests the case of SOC with phases. The case of the NL contribution to forces and the current is now also tested, to avoid this to occur again in the future.

An unsupported output option is also now prevented to be requested.

Closes #607 (closed)

News snippet

Fixes SOC on GPUs

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.