DaVinci Resolve 18.5 support + make rockylinux 8.6 the default distro

[fat-tire]

Per issue #33, this PR is meant to support the upcoming 18.5 DaVinci Resolve (DVR) release.

• Adds new packages required by 18.5 (beta 1)
• Set default linux distribution in the container to Rockylinux 8.6 (which auto-updates to 8.7). This is BMD's preferred distro. (If pipewire is unavailable on host, default container linux is not changed from centos stream 8 until someone without pipewire on their host can test rockylinux 8.6 and confirm it works.)
• Add compat-openssl 1.0 for onboarding app in Rockylinux 8.6 (and where supported elsewhere).
• Some packages (compat-openssl 1.0 & 1.1 + libxcrypt-compat) exist on some distributions but not on others, so now checking before installing.
• x264 export plugin build: Use "crb" package repository when available, "powertools" otherwise
• Update the NVIDIA_VERSION default
• add --refresh to dnf update command in Dockerfile because why not

Tested with: Rockylinux 8.6, Alma Linux 9.1, and Centos 9 stream w/ DVR 18.5 with both Podman and Docker. (Hopefully it doesn't break DVR 18.1.)

These changes could probably be more efficient in places, but they seem to work.

Please submit any changes along and/or reports of success/failure. Thx!

[fat-tire]

Forgot to add "ed" to the requirements for building the codec plugin per #33 discussion and also needed to update rockylinux:8.6 in one other place. These are now fixed and I'll test and push it tomorrow, then probably merge the PR.