Refactor tokenization coding tree
Refactor tokenization coding tree

Expand the tokenization tree writing to support per transform block
type coding in next CLs.

Change-Id: I3560e658f89cc500eb49603f95dd2b4e99045f5b

mbebenita/aom,GrokImageCompression/aom,mbebenita/aom,smarter/aom,GrokImageCompression/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,mbebenita/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,mbebenita/aom,GrokImageCompression/aom,smarter/aom,mbebenita/aom,smarter/aom,mbebenita/aom,smarter/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,mbebenita/aom,GrokImageCompression/aom