Merge pull request grpc#18301 from srini100/v1.19.x

V1.19.x

Merge pull request grpc#18166 from muxi/bump-protocompiler

ObjC v1.19.0 batch patch

Merge pull request grpc#18035 from srini100/v1.19.x

Bump version to pre1

Merge pull request grpc#17712 from sanjaypujare/releasing-v1.18.x

Releasing v1.18.x

Merge pull request grpc#17627 from sanjaypujare/releasing-v1.18.x

Change the version suffix from dev to pre1 and regenerate projects

Merge pull request grpc#17446 from moriarty/cherry-pick-fix-bazel-0.20

Cherry pick fix bazel 0.20

Merge pull request grpc#17483 from srini100/v1.17.x

bump to v1.17.1

Merge pull request grpc#17426 from srini100/v1.17.x

V1.17.x

Merge pull request grpc#17381 from muxi/v1.17.x

Bump version to v1.17.0

Merge pull request grpc#17319 from stanley-cheung/bump-to-pre3

Bump to v1.17.0-pre3