feat(eval api): (2.2/n) delete eval / scoring / scoring_fn apis (#1700)

# What does this PR do?
- To make it easier, delete existing `eval/scoring/scoring_function`
apis. There will be a bunch of broken impls here. The sequence is:
1. migrate benchmark graders
2. clean up existing scoring functions

- Add a skeleton evaluation impl to make tests pass. 

## Test Plan
tested in following PRs

[//]: # (## Documentation)

docs/source/distributions/remote_hosted_distro/nvidia.md

@@ -7,10 +7,8 @@ The `llamastack/distribution-nvidia` distribution consists of the following prov
 |-----|-------------|
 | agents | `inline::meta-reference` |
 | datasetio | `inline::localfs` |
-| eval | `inline::meta-reference` |
 | inference | `remote::nvidia` |
 | safety | `remote::nvidia` |
-| scoring | `inline::basic` |
 | telemetry | `inline::meta-reference` |
 | tool_runtime | `inline::rag-runtime` |
 | vector_io | `inline::faiss` |