New STS3+STS5 geometry

In this geometry version, we have introduced the gap of 2 cm between the STS3 and STS5 blocks. The first three stations are located in the same position as they are in the STS v21e. Stations 4-8 are moved by 2cm to the downstream side due to the gap increased between STS3 and STS5 blocks. The box size in the Z direction remained the same. However, there is a only change in the box size in the XY direction. There is a box included around the STS3 block and also an additional C-frame between the STS3 and STS5 blocks. There is no beampipe flange included on the backside of the STS wall. This geometry only be used with a new magnet design which otherwise will show some overlaps.