Added Extensions for named params(BridgeParameter)

[canewsin]

and BridgeTypeAnnotation & BridgeTypeRef wrappers. to reduce code size

Improvements: Uses extensions to reduce code verbosity

[ethanblake4]

This is super cool! A few things:

• Extensions should indeed be in dart_eval repo if you can move it over
• Instead of wrapped can you use param to indicate that this is creating parameters specifically? Thanks!

[ethanblake4]

Closing in favor of https://github.com/ethanblake4/dart_eval/pull/84