[test][digest] Relocate unit tests to exist alongside source

Change-Id: Ib244d3afefbad49c5534bf71882c7f21ceff3b9b

zircon/system/utest/digest/BUILD.gn → zircon/system/ulib/digest/test/BUILD.gn

@@ -2,6 +2,13 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+group("test") {
+  testonly = true
+  deps = [
+    ":digest",
+  ]
+}
+
 test("digest") {
   sources = [
     "digest.cpp",

zircon/system/utest/BUILD.gn

@@ -59,6 +59,7 @@ if (current_cpu != "") {
       "$zx/system/ulib/c:tests",
       "$zx/system/ulib/cobalt-client/test",
       "$zx/system/ulib/ddk:ddk-unittest",
+      "$zx/system/ulib/digest/test",
       "$zx/system/ulib/disk-inspector/test",
       "$zx/system/ulib/driver-integration-test/test",
       "$zx/system/ulib/fvm/test",
@@ -95,7 +96,6 @@ if (current_cpu != "") {
       "debugger",
       "devfs",
       "device-enumeration",
-      "digest",
       "dlfcn",
       "dlopen-indirect-deps",
       "driver-test",