Java: Add query for counting sink model instances

Also adds a more sensible ordering to the existing queries.

java/ql/src/Telemetry/AutomodelAlertSinkUtil.qll

@@ -78,7 +78,7 @@ class SinkModel extends TSinkModel {
 }
 
 /** An expression that may correspond to a sink model. */
-private class PotentialSinkModelExpr extends Expr {
+class PotentialSinkModelExpr extends Expr {
   /**
    *  Holds if this expression has the given signature. The signature should contain enough
    *  information to determine a corresponding sink model, if one exists.

java/ql/src/Telemetry/AutomodelAlertSinks.ql

@@ -13,4 +13,4 @@ from int alertCount, SinkModel s
 where sinkModelTally(alertCount, s) and s.getProvenance() = "ai-generated"
 select alertCount, s.getPackage() as package, s.getType() as type, s.getSubtypes() as subtypes,
   s.getName() as name, s.getSignature() as signature, s.getInput() as input, s.getExt() as ext,
-  s.getKind() as kind, s.getProvenance() as provenance
+  s.getKind() as kind, s.getProvenance() as provenance order by alertCount desc

java/ql/src/Telemetry/AutomodelAlertSinksPerQuery.ql

@@ -16,3 +16,4 @@ where
 select queryId, alertCount, s.getPackage() as package, s.getType() as type,
   s.getSubtypes() as subtypes, s.getName() as name, s.getSignature() as signature,
   s.getInput() as input, s.getExt() as ext, s.getKind() as kind, s.getProvenance() as provenance
+  order by queryId, alertCount desc

java/ql/src/Telemetry/AutomodelCountGeneratedSinks.ql

@@ -0,0 +1,18 @@
+/**
+ * @name Number of instances of each sink model
+ * @description Counts the number of instances of `ai-generated` sink models.
+ * @kind table
+ * @id java/ml/metrics-count-instances-per-sink-model
+ * @tags internal automodel metrics
+ */
+
+private import java
+private import AutomodelAlertSinkUtil
+
+from int instanceCount, SinkModel s
+where
+  instanceCount = strictcount(PotentialSinkModelExpr p | p.getSinkModel() = s) and
+  s.getProvenance() = "ai-generated"
+select instanceCount, s.getPackage() as package, s.getType() as type, s.getSubtypes() as subtypes,
+  s.getName() as name, s.getSignature() as signature, s.getInput() as input, s.getExt() as ext,
+  s.getKind() as kind, s.getProvenance() as provenance order by instanceCount desc