Make G4XrayBoundary process available


### Discussed in https://github.com/OpenGATE/opengate/discussions/671

<div type='discussions-op-text'>

<sup>Originally posted by **ZacharyEBirch** January 21, 2025</sup>
As the title states, is xraylib available/integrated with Gate 10 as it is with Gate 9?
I know they (xraylib) have a pip package currently available. </div>