Add "assets" resolver to GrapheneAssetSelection (#19771)

Summary:
Will allow us to break out the list of asset keys in the sensor view by
whether or not they have an AMP policy.

Test Plan: BK

## Summary & Motivation

## How I Tested These Changes

python_modules/dagster-graphql/dagster_graphql/schema/asset_selections.py

@@ -3,13 +3,15 @@
 from dagster._core.definitions.external_asset_graph import ExternalAssetGraph
 from dagster._core.host_representation.external import ExternalRepository
 
+from ..implementation.fetch_assets import get_asset_nodes_by_asset_key
 from .asset_key import GrapheneAssetKey
 from .util import non_null_list
 
 
 class GrapheneAssetSelection(graphene.ObjectType):
     assetSelectionString = graphene.String()
     assetKeys = non_null_list(GrapheneAssetKey)
+    assets = non_null_list("dagster_graphql.schema.pipelines.pipeline.GrapheneAsset")
 
     def __init__(self, asset_selection: AssetSelection, external_repository: ExternalRepository):
         self._asset_selection = asset_selection
@@ -25,5 +27,16 @@ def resolve_assetKeys(self, _graphene_info):
             for asset_key in self._asset_selection.resolve(asset_graph)
         ]
 
+    def resolve_assets(self, graphene_info):
+        from dagster_graphql.schema.pipelines.pipeline import GrapheneAsset
+
+        asset_graph = ExternalAssetGraph.from_external_repository(self._external_repository)
+        asset_nodes_by_asset_key = get_asset_nodes_by_asset_key(graphene_info)
+
+        return [
+            GrapheneAsset(key=asset_key, definition=asset_nodes_by_asset_key.get(asset_key))
+            for asset_key in self._asset_selection.resolve(asset_graph)
+        ]
+
     class Meta:
         name = "AssetSelection"

python_modules/dagster-graphql/dagster_graphql_tests/graphql/test_sensors.py

@@ -155,6 +155,16 @@
         assetKeys {
           path
         }
+        assets {
+          key {
+            path
+          }
+          definition {
+            assetKey {
+              path
+            }
+          }
+        }
       }
     }
   }
@@ -1420,3 +1430,9 @@ def test_asset_selection(graphql_context):
     assert result.data["sensorOrError"]["assetSelection"]["assetKeys"] == [
         {"path": ["fresh_diamond_bottom"]}
     ]
+    assert result.data["sensorOrError"]["assetSelection"]["assets"] == [
+        {
+            "key": {"path": ["fresh_diamond_bottom"]},
+            "definition": {"assetKey": {"path": ["fresh_diamond_bottom"]}},
+        }
+    ]