sourcekitd/test: add test for cursor-info returning group name for user modules

Author: nkcsgexi

test/SourceKit/CursorInfo/Inputs/group.json

@@ -0,0 +1,5 @@
+{
+  "GroupA": [
+    "FooSwiftModule.swift",
+  ]
+}

test/SourceKit/CursorInfo/cursor_user_module_group.swift

@@ -0,0 +1,9 @@
+// RUN: %empty-directory(%t.mod)
+// RUN: %target-swift-frontend -module-name MyModule -emit-module -emit-module-path %t.mod/MyModule.swiftmodule  -emit-module-doc -emit-module-doc-path %t.mod/MyModule.swiftdoc -group-info-path %S/Inputs/group.json %S/Inputs/FooSwiftModule.swift
+
+// RUN: %sourcekitd-test -req=cursor -pos=7:10 %s -- %s -I %t.mod | %FileCheck -check-prefix=CHECK %s
+
+import MyModule
+_ = fooSwiftFunc()
+
+// CHECK: <Group>GroupA</Group>