Add a new build Environment option for CondaBuild to improve conda-built artifacts

[jleibs]

What

Resolves:

• Examples link to wrong rrd files when built on conda-forge #3908

The main issue is that the conda environment dind't realize it was building a released version.

The conda build environment is special. The feedstock recipe downloads the source from the published artifact, so many of our checks related to things like branch-name aren't correct. Otherwise it's very close to the CI build environment.

This detects the environment and attempts to do more reasonable things where relevant.

Testing

• I created a temporary branch in the rerun feedstock repository pointing to the source https://github.com/rerun-io/rerun/archive/refs/heads/jleibs/conda_examples.zip
• I built using python build-locally.py linux_64_python3.10.____cpython
• I ran the rerun version from the channel with RUST_LOG=debug
• Confirmed correct attempted download location based on version:
  • Downloading .rrd file from "https://demo.rerun.io/version/0.10.0-alpha.7+dev/examples/plots/data.rrd"…

Related, I also need to remove RERUN_IS_PUBLISHING from the conda recipe. See:

• Remove RERUN_IS_PUBLISHING and bump to 0.10.0 conda-forge/rerun-sdk-feedstock#17

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested demo.rerun.io (if applicable)
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG

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