Allow system level metadata information

[DhairyaLGandhi]

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

Additional context

Ref #3734

Add any other context about the problem here.

Are there cases where there are expression evaluations anywhere for the model parsing? Currently everything is delayed, but that means local variables are not referred to properly, and esc will simply convert the escaped expression, whereas we need it as parse/ expansion time.