* Support for adding reviewer role
* show reviewer in track changes user list
* added "review" in assertClientCanViewProject
* test if reviewer can read project
* added collaboratorsGetter tests
* eit toggle-track-changes when track changes changes
* [real-time] ensure tc is enabled when reviewer role is used
* use assertClientCanReviewProjectAndDoc, refactor _assertClientCanApplyUpdate
GitOrigin-RevId: 158bd1ff0d4b4977da950134f8ad8b3740855290