feat(rag): eval relevancy conventions (#1612)

* feat(rag): eval relevancy semantic conventions

* add precision at K

* move to eval conventions

* fix precision

* Update src/phoenix/trace/evaluation_conventions.py

Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>

* Update src/phoenix/trace/evaluation_conventions.py

Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>

* Update src/phoenix/trace/evaluation_conventions.py

Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>

* update relevancy_ratio

* remove ratio as it is a dupe of precision

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Co-authored-by: Roger Yang <80478925+RogerHYang@users.noreply.github.com>