version bump to 11, dev builds, timeouts and other improvements.

 - mac runners have ant installed, brew/cache isn't needed anymore.
 - added cache for platform-src build
 - bump JDK version of migrated jobs to 11 where possible
 - extract java distribution variable
 - increase pipeline artifact retention time from 1 to 2 days
 - added per-job timeouts (at least 2x of average runtime; 1h minimum)
 - always run the paperwork job
 - set continue-on-error for java.mx.project false in PRs
 - wrapped platform/core.startup, java/java.editor, java.lsp.server
   in retry script
 - ci:dev-build will now produce a dev-build zip artifact
 - setup all JDKs at the start of the job for consistent timestamp