Refactored namespaces to use maps of objects

[jaredoconnell]

Also refactored the namespace fields to have defaults provided in the ScalarType struct

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[webbnh]

Overall, this change looks excellent. However, I have a couple of concerns.

First, I appreciate the test clean-up in schema/bool_test.go; however, when we are refactoring code, we should really try to avoid making changes to the tests. (And, I have several other comments on the changes there, as well.)

Second, it seems like the changes to PatternSchema should be analogous to the ones to StringSchema.

Beyond those comments, it looks like there might be some engine fallout from this:

• It looks like InvalidSerializationDetectorSchema should probably also get the ScalarType treatment.
• There are a few references to DEFAULT_NAMESPACE.
• There are a number of references to ApplyScope() which might need or want tweaking:
  • anySchemaWithExpressions.ApplyScope()? (That looks like it's passing a scope where it should be passing a map of objects.)
  • There are calls to ApplyScope() in processInput() and applyAllNamespaces()?

And, I have a few other comments/questions/nits.

[jaredoconnell]

Everything should be addressed. I also added a comment to the ScalarType struct.

[webbnh]

Looks good...except I found a typo that you should fix and I'm hoping that we can remove an if statement.

[webbnh]

Looks good...unless you missed one.