Commit summary:
340e082 build.make: optional inclusion of Windows in multiarch images
5231f05 build.make: properly declare push-multiarch
4569f27 build.make: fix push-multiarch ambiguity
bd41690 cloud build: initial set of shared files
6f2322e Update patch release notes generation command
d8c76fe Support local snapshot RBAC for pull jobs
ea1f94a update release tools instructions
7edc146 Update snapshotter to version 2.0.1
3863a0f build for multiple platforms only in CI, add s390x
7c5a89c prow.sh: use 1.3.0 hostpath driver for testing
