Fix #99: Implement getTypeCode() for compat SBase inheritors

[dyrpsf]

Overview

This PR resolves Issue #99 by implementing the getTypeCode() method for all SBase inheritors within the libsbml-compat module, returning the appropriate integer constants to mirror the C++ libSBML API.

Changes Made

• Created the missing libsbmlConstants.java interface to house the standard SBML_* integer type codes.
• Added the getTypeCode() method to Species, Compartment, Model, SBMLDocument, and ListOfSpecies within the compatibility module.
• Fixed a pre-existing broken import (org.sbml.jsbml.xml.test.SBML_L2V1Test) in SBMLDocument.java that was preventing the module from compiling.
• Fixed a pre-existing missing import for MessageFormat in ListOfSpecies.java.
• Fixed pre-existing missing throws XMLStreamException declarations on the Notes wrapper methods in Compartment.java.

Validation

• Successfully compiled the libsbml-compat module.
• Passed all module tests.

Closes #99