Merge branch 'stable-3.1' into stable-3.2

* stable-3.1:
  Bump Bazel version to 3.5.0
  Upgrade bazlets to latest stable-3.1 to build with 3.1.8 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.12 API
  Upgrade bazlets to latest stable-2.16 to build with 2.16.22 API

Change-Id: Id87bcb0ead4f7c516c2d9cdf0c7020445f682fe7