[Evals API][6/n] meta-reference llm as judge, registration for ScoringFnDefs (#330)

* wip scoring refactor

* llm as judge, move folders

* test full generation + eval

* extract score regex to llm context

* remove prints, cleanup braintrust in this branch

* change json -> class

* remove initialize

* address nits

* check identifier prefix

* udpate MANIFEST

tests/examples/evals-tgi-run.yaml

@@ -33,6 +33,10 @@ providers:
     provider_type: remote::tgi
     config:
       url: http://127.0.0.1:5009
+  - provider_id: tgi1
+    provider_type: remote::tgi
+    config:
+      url: http://127.0.0.1:5010
   memory:
   - provider_id: meta-reference
     provider_type: meta-reference