Move the BODR (periodic table) data into a private header.

Rather than install, attempt to locate, parse, etc the elements.xml
file directly, embed the data in the vtkBlueObeliskData translation
unit via the vtkBlueObeliskDataInternal header.

The header file is generated by the GenerateBlueObeliskHeader test
in Domains/Chemistry, which is built by enabling the CMake option
1 job for embed_bodr
Status Job ID Name Coverage
passed kwrobot-commit-check