ETABS_Toolkit: Add apply Modifiers for elements

[nirbhay93]

No description provided.

[IsakNaslundBh]

This could be implemented after BHoM/BHoM#578

By adding a SectionModifier fragment to a bar instead of a section property

[maryannewachter]

This works based on the defined section properties, but not on a per object basis. This can be somewhat confusing because the object section modifiers and section property modifiers are multiplicative, and the object itself only lists the object defined property modifiers.

[mchaf]

Assigning property modifiers to individual elements would be quite useful for any ETABS workflow, especially with concrete. Workflows can be created with property modifiers on specific section properties, but this, as Maryanne stated above, would be quite confusing, as this is not the typical workflow. It would be prefered to have individual element modifiers.