feature: go to implementations for dependency sources

metals-bench/src/main/scala/bench/MetalsBench.scala

@@ -99,6 +99,20 @@ class MetalsBench {
     }
   }
 
+  @Benchmark
+  @BenchmarkMode(Array(Mode.SingleShotTime))
+  def typeHierarchyIndex(): Unit = {
+    scalaDependencySources.inputs.foreach { input =>
+      implicit val rc: ReportContext = EmptyReportContext
+      new ScalaToplevelMtags(
+        input,
+        includeInnerClasses = true,
+        includeMembers = false,
+        dialects.Scala213,
+      ).index()
+    }
+  }
+
   @Benchmark
   @BenchmarkMode(Array(Mode.SingleShotTime))
   def scalaTokenize(): Unit = {

metals/src/main/resources/db/migration/V5__Jar_type_hierarchy.sql

@@ -0,0 +1,14 @@
+-- Type hierarchy information, e.g. symbol: "a/MyException#", extended_name: "Exception"
+create table type_hierarchy(
+  symbol varchar not null,
+  parent_name varchar not null,
+  path varchar not null,
+  jar int,
+  is_resolved bit,
+  foreign key (jar) references indexed_jar (id) on delete cascade
+);
+
+create index type_hierarchy_jar on type_hierarchy(jar);
+
+alter table indexed_jar
+add type_hierarchy_indexed bit