Completion fixes

Cleaning up some rough edges with completion list:
* completion on call/new expressions
* completions in type positions
* completions on module exports
* filtering private member completions based on location
* disable completion list in with blocks
* completion for object literal property names based on contextual type
* completions before keywords

There changes were driven by tests, so tests were all enabled in the beginning. sorry if this makes it harder to review changes.

I could but I would rather not. the problem would be in the future, if for whatever reason isReservedWord implementation uses this, it will break. this is also an error case, and not a main line scenario, so I am not too concerned about perf.