Add rhel8-package.yml that builds a RHEL8 install package from a tag
using the prebuilt RHEL8 CI container. It configures with an install
prefix, builds the install target, runs the CPack package target, and
uploads the resulting *.tar.gz as the ResInsight-RHEL8 artifact.
Wire the new workflow into release-draft.yml so the draft release waits
for the RHEL8 package run and attaches the *.tar.gz directly, alongside
the existing zipped platform artifacts.
On a tag push, wait for the Windows/Linux build (ResInsightWithCache.yml)
and the macOS build (ResInsightMac.yml) to finish, download their
application artifacts, zip them per platform, and create a draft GitHub
Release with the archives attached for maintainer review.
Magne Sjaastad