EDK: Split the mojo_edk_system_unittests target.

mojo/tools/data/unittests

 # This file contains a list of Mojo gtest unit tests.
 # This must be valid python. It can use the |config| global that will be a
 # mopy.config.Config object and must set a |tests| global that will contain the
 # tests to run.
 # TODO(vtl): Add a way of specifying data dependencies instead of cacheable.
 
 tests = [
-  # System tests:
+  # EDK tests:
+  {
+    "test": "mojo_edk_embedder_unittests",
+  },
   {
     "test": "mojo_edk_system_unittests",
   },
+  {
+    "test": "mojo_edk_system_test_unittests",
+  },
+  {
+    "test": "mojo_edk_util_unittests",
+  },
 
   # Public tests:
   {
     "test": "mojo_public_bindings_unittests",
     "cacheable": False,
   },
   {
     "test": "mojo_public_environment_unittests",
   },
   {
@@ skipping 75 matching lines @@
       "cacheable": False,
     },
   ]
 
 if config.target_os == config.OS_LINUX:
   tests += [
     {
       "test": "sandbox_linux_unittests",
     },
   ]