High level issue for building v15 geometry

[tvami]

Is your feature request related to a problem? Please describe.

We need a new geometry for several reasons. Opening this as an issue for collecting sub-issues

Describe the solution you'd like

• Add air: done in https://github.com/LDMX-Software/ldmx-sw/pull/1514
• Add support structure: sub-issue https://github.com/LDMX-Software/ldmx-sw/issues/1435
• Move ECal to have 32 layers
• Add shifted tracker to have space for LYSO
• Same for TS
• etc

[tvami]

I did what I could, I have no idea how to do the light pipes, SiPMs, and support structure so somebody else will have to do that