Automated PRs for release builds

Currently it is hard to keep track of release builds as not all versions get GAed at the same time, builds for some arches can be delayed and in some cases we have re-releases with minor version updates as well. Also the dockerfile updates usually have >450 files which makes it difficult to review. The proposal here is to have the following

1. Have a nightly jenkins job to call `update_all.sh` only for release builds and generate a PR to the openjdk-docker repo if the shasums have changed.
2. Add a check to the PR testing scripts that validates the Dockerfiles for
a. version mismatches among the various dockerfiles
b. missing arches in the dockerfiles
3. Provide a daily summary "table" in the nightly builds that provide a quick visual summary of the builds (>200 builds)
a. Arch-wise table that highlights any builds failures
b. Append data for each version in the `./build_all.sh` loop against hotspot/openj9, jdk/jre
c. Table gets printed at the end of the run, so easy to get a summary at the end of the logfile