Allow for separate inboard and outboard first wall builds

Description of issue / requirement to address

PROCESS currently only assumes an identical inboard and outboard first wall in terms of pipe size, pitch armour etc.
It would be good to enable a separate set of variables for the inboard and outboard builds. This will allow for more accurate radial builds and pumping requirements.

• Will need to check blanket changes.

• Possibly add different fw_wall variations for plasma and non-plasma facing sides

• Will only affect the geometry, not the functionality with the blanket and coolants. That will come later

Proposed solution

Create a separate set of variables for the inboard and outboard FW parameters