Robot_Toolkit: Issue with pushing gravity loads with named groups

[jdarcyBHE]

Trying to push gravity loads for all bars.Potential source of error: The gravity loads BHoM component will only accept a group of BHoMObjects not Bars, thus when pushed to Robot it is unable to assign the object correctly. Error message '1. Solution exception:Object reference not set to an instance of an object.'

[IsakNaslundBh]

Problem here seem to be coming from putting a name on the group:

Doing this, the adapter tries to find a predefined group in Robot rather than using the objects, and as there was no group named like this, it crashes, which is a bug that needs to be fixed, but less severe.

Using the gravity load comp that takes a IEnumerable instead of a group, or not naming the group, things seem to be working as expected.

[IsakNaslundBh]

This can be tackled together with #238 as both relates to pushing of gravity loads