[WIP] Centralize `yaml` configurations into `conda_build.yaml`

[kenodegard]

Description

PyYAML uses interesting defaults that we've often sought to override (e.g., yaml.dump(default_flow_style=False)). To ensure we do a better job of consistently applying the same standard to all of our yaml.load/yaml.dump calls we introduce conda_build.yaml with all of our customizations.

Extends https://github.com/conda/conda-build/pull/5284

Checklist - did you ...

• [ ] Add a file to the news directory (using the template) for the next release's release notes?
• [x] Add / update necessary tests?
• [ ] ~Add / update outdated documentation?~

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #5285 will not alter performance

_{Comparing kenodegard:yaml (52aae52) with main (b1310ca)}

Summary

✅ 3 untouched benchmarks