Update Fbc V3 package

[fbergmann]

Description

The FBC v3 package needed to be updated to reflect the latest spec

Motivation and Context

the PR introduces

• reaction2 on FluxObjective
• variable2 on UserDefinedConstraintComponent

it also fixes the type of coefficient on the UserDefinedConstraintComponent, since it was a double while
the specification prescribes it to be a SIdRef

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Change in documentation

Checklist:

• I have updated all documentation necessary.
• I have checked spelling in (new) comments.

Testing

• Testing is done automatically and codecov shows test coverage
• This cannot be tested automatically

[fbergmann]

the one failing test is due to a test runner not being able to install SWIG. this has no influence to the code here.