make default conda environment name the plugin name

[gregcaporaso]

Currently the default environment name is based on the distro and epoch. For example, see the default install instructions for genome-sampler in the screenshot below. The recommended environment name is already one that I have, and I think this could get really confusing for people who have multiple distros. I think better would be the plugin name, or maybe plugin-distro-epoch (e.g., genome-sampler-amplicon-2024.10 in this case).