feat: Updates to work towards a GA release

What was the problem/requirement? (What/Why)

deadline-cloud-for-cinema-4d is an "alpha release" and during my testing trying to get this up and running on a customer managed fleet on AWS I have had to make several changes to get it working correctly.

What was the solution? (How)

Each of these commits are aimed to be mostly separate features or fixes however in my testing some of them do build on others.

Add COMMANDLINE_EXECUTABLE env var This implements optional environment variable overrides to point to a custom "Commandline" installation.
Forcefully add the dll path for C4D python Implement some DLL patching required for versions of C4D below 2024.2. See https://github.com/danbradham/wheels/issues/4#issuecomment-1772721170
Creating an adaptor script wrapper for Linux On Linux, C4D requires environment variables set up and they provide a setup_c4d_env script which mostly works. We've built an adaptor.sh for Linux to run with will apply the setup_c4d_env script. This also introduces some environment variable changes that I found from Deadline10.
Include a patch for versions below 2024.4 This patch will add /usr/lib64 to the LD_LIBRARY path if the C4D version is below 2024.4. Versions lower than this had an issue where c4dplugin.xso64 required libwebkit2gtk even in a headless -nogui mode.
Add a better safety around the os.environ call A quick fix around querying for an environment variable that may be None.

How was this change tested?

I have been working with and using farm-2573f61b9d784c7fa38e61dbdc39172f to do all of my testing. This testing implements fixes that get us ready for a Linux render node worker, but currently appear to only work for 2024+. I have tested it on R26 and am getting hanging on launch (unrealted to Deadline as far as I can tell). Once I determine how to get that working, I will implement another PR with R26 fixes potentially.

Was this change documented?

Yes see DEVELOPMENT.md

Is this a breaking change?

No, the Linux support is a feature and the environment variable support is an optional feature

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aws-deadline / deadline-cloud-for-cinema-4d