feat: introduce typed transformation problem reporting

[jimmarino]

What this PR changes/adds

In an effort to make transformation problem reporting consistent across the codebase, this PR introduces the PoblemBuilder, which provides a way to construct transformation problems in a typed way.

Specifically, TransformationContext now includes a problem() method that returns a ProblemBuilder. The build can be used to report transformation errors:

       context.problem()
                    .missingProperty()
                    .type(DSPACE_NEGOTIATION_CONTRACT_REQUEST_MESSAGE)
                    .property(DSPACE_NEGOTIATION_PROPERTY_PROCESS_ID)
                    .report();

The builder will then construct the problem string and report it to the context. Different categories of problems can be reported: MISSING PROPERTY, NULL PROPERTY, INVALID PROPERTY, UNEXPECTED TYPE.

All transformers have been updated to use this typed access. Only a few, specialized cases use the existing reportProblem(String problem) method.

This PR also fixes a few bugs in the transformers encountered when updated to typed problem reporting.

Linked Issue(s)

Closes #2909

Checklist

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