packages/apps/Settings: Set LOCAL_SDK_VERSION where possible.

This change sets LOCAL_SDK_VERSION for all packages where
this is possible without breaking the build, and
LOCAL_PRIVATE_PLATFORM_APIS := true otherwise.

Setting one of these two will be made required soon, and this
is a change in preparation for that. Not setting LOCAL_SDK_VERSION
makes the app implicitly depend on the bootclasspath, which is
often not required. This change effectively makes depending on
private apis opt-in rather than opt-out.

Test: make relevant packages
Bug: 73535841
Change-Id: Ic906adbd670c4dbfe2cdf0b71cdbeaf9ac08a27e
diff --git a/Android.mk b/Android.mk
index c59d938..cb856ce 100644
--- a/Android.mk
+++ b/Android.mk
@@ -12,6 +12,7 @@
 include $(CLEAR_VARS)
 
 LOCAL_PACKAGE_NAME := Settings
+LOCAL_PRIVATE_PLATFORM_APIS := true
 LOCAL_CERTIFICATE := platform
 LOCAL_PRIVILEGED_MODULE := true
 LOCAL_MODULE_TAGS := optional