Implement non-function type alias support in Kythe

[leafpetersen]

This issue tracks support of the non-function type alias feature. See the enclosing meta-issue for details.

cc @davidmorgan @mit-mit @franklinyow

[davidmorgan]

Thanks; b/179969218

[leafpetersen]

This is tracked internally and my understanding is that we will not block on this - indexing will land after we turn this on internally.