Barrel ECal: Implement full frames for the AstroPix slots

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

AstroPix frames do not have vertical walls in the current implementation, only horizontal.

**Describe the solution you'd like**

Implement frames as 2 trapezoids, one make of carbon fiber, second filled with air placed inside the first one and smaller of `EcalBarrel_CarbonThickness`. Then the staves need to be placed inside the second air-filled trapezoid. Something like that was done by @Chao1009 in this version of the `barrel_interlayers.xml`: https://github.com/eic/epic/commit/e1cee1f0b2176d8a0d47c07cdac63beb74bf59bb, but then it was changed to the top and bottom part of the frame only.

**Describe alternatives you've considered**
No alternatives

**Additional context**
See the illustration below:


Start by inspecting barrel_interlayers.xml and the AstroPix slot and stave geometry it references. Compare the earlier implementation in commit e1cee1f0b2176d8a0d47c07cdac63beb74bf59b; done means the frames have the requested vertical trapezoidal carbon-fiber and air parts, with staves placed inside the inner air trapezoid.

Written by the indexing model from the issue text.