Package a phoenix2 "pathfinder" library using conda

The conda-build tool is been abandoned because better alternative have been implemented by the community. The mamba-org developped boa, but deprecated it in favor of rattler-build backed by prefix.dev.

Some documentation:

• rattler-build introduces a new conda package recipe format
• dependencies documentation for explanations of the different dependencies sections
• package specification
• advanced configuration and variants

Tasks:

• #9 (closed) - Build a phoenix pathfinder package with no dependency on other phoenix packages using rattler-build
• #10 (closed) - Implement the package building as part of the CI of pathfinder repository and upload to prefix.dev channels
• #11 (closed) - Implement "workflow" compatible package building in CI: build packages per branch, release packages on git tags, etc.

FYI @paubert