Remove HiddenApiAccessFlags, move content to hiddenapi::

Hiddenapi code in runtime/ has all code in the hiddenapi:: namespace
instead of using a class as a wrapper. Refactor HiddenApiAccessFlags
for consistency. Also turn ApiList into `enum class` for stricter
type checks.

Test: m test-art
Change-Id: Ifb3c443ea43860476abd4fd3d4934cd14e2cdcc1
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 0247e4e..151f7b8 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -3395,8 +3395,8 @@
   // also set its runtime hidden API access flags.
   uint32_t access_flags = field.GetAccessFlags();
   if (klass->IsBootStrapClassLoaded()) {
-    access_flags = HiddenApiAccessFlags::EncodeForRuntime(
-        access_flags, static_cast<HiddenApiAccessFlags::ApiList>(field.GetHiddenapiFlags()));
+    access_flags = hiddenapi::EncodeForRuntime(
+        access_flags, static_cast<hiddenapi::ApiList>(field.GetHiddenapiFlags()));
   }
   dst->SetAccessFlags(access_flags);
 }
@@ -3418,8 +3418,8 @@
   // also set its runtime hidden API access flags.
   uint32_t access_flags = method.GetAccessFlags();
   if (klass->IsBootStrapClassLoaded()) {
-    access_flags = HiddenApiAccessFlags::EncodeForRuntime(
-        access_flags, static_cast<HiddenApiAccessFlags::ApiList>(method.GetHiddenapiFlags()));
+    access_flags = hiddenapi::EncodeForRuntime(
+        access_flags, static_cast<hiddenapi::ApiList>(method.GetHiddenapiFlags()));
   }
 
   if (UNLIKELY(strcmp("finalize", method_name) == 0)) {