Polarization from Miller indices

Description

Allow to define the laser polarization in terms of Miller indices. For this, one must provide the variable MillerIndicesBasis that contains the reduced coordinates of the X, Y, and Z high symmetry points. This is useful when the crystal are arbitrarily rotated. The coordinates of the points can easily be obtained using for instance XCrysden.

News snippet

Allow to define the laser polarization in terms of Miller indices.

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.