Update abstractsystem.jl with :get_name

[cadojo]

The get_name method was missing from the getter list; this commit adds :name to the getter generation block.

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the
  contributor guidelines, in particular the SciML Style Guide and
  COLPRAC.
• Any new documentation only uses public API