Update release notes to 11.0.20.0+8
Drop local inclusion of JDK-8274864 & JDK-8305113 as they are included in 11.0.20+1
Bump tzdata requirement to 2023c now it is available in the buildroot
Bump bundled LCMS version to 2.15 as in jdk-11.0.20+1.
Bump bundled HarfBuzz version to 7.0.1 as in jdk-11.0.20+7
Use tapsets from the misc tarball
Introduce 'prelease' for the portable release versioning, to handle EA builds
Make sure root installation directory is created first
Use in-place substitution for all but the first of the tapset changes
Sync the copy of the portable specfile with the latest update
Add note at top of spec file about rebuilding
** This tarball is embargoed until 2023-07-18 @ 1pm PT. **
Related: RHEL-30918
