DFT+U+V commutator with spinors

Description

Adding the support of the commutator of the position operator and the +U+V nonlocal operator for spinors. Tests are added to cover the DFT+U+V with spinors.

News snippet

Adding the support of the commutator of the position operator and the +U+V nonlocal operator for spinors.

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.

testsuite/lda_u/10-intersite.03-Na2_spinors.inp

 CalculationMode = gs
 ExperimentalFeatures = yes
 FromScratch = yes
+DisableAccel = yes
 
 dist = 3.0