Expose code builder on generator result, and some tidying up
Fix inherited TagHelper properties.

- Used to only look at declared properties on the tag helper type, now we get the runtime properties.
- Fixed Runtime test projec to work with new CLR changes (looks like it was missed).

#189
Modify CSharpCodeWriter to generate async lambdas for section

Fixes #85
Modifications to support providing tag descriptors from derived hosts
Adding unit tests and responding to PR comments