feat(analyzer): Implement parameter type annotations

[andrewmbenton]

A first step towards implementing #2800.

I'd like to add some more tests to meta_test.go if I have time.

Some things to consider before merging:

1. What to do about the additional comments? If you look at the test output you'll see that the new comments end up in generated source. Should we swallow them?
2. Should I implement the forcenotnull thing with a map instead of a pointer to a bool? Might be simpler...

The changes to ParamRef are pure refactor.

[kyleconroy]

• Add a test for array types
• Verify types if the database analyzer is active
• Switch the bool* to an enum