Expose AndroidPackage#getStorageUuid

The system internally passes around a String, but to mirror the
public ApplicationInfo API, PackageState and related
infrastructure will act on real UUIDs.

These can be converted with StorageManager#convert, although it's
expected that any exposed @SystemApi methods will just take the
UUID as a paramter.

Bug: 254029038

Test: atest AndroidPackageTest

Change-Id: I93e0f04b4d5c93cd534d393057f2c0d7f61418df
diff --git a/services/api/current.txt b/services/api/current.txt
index 35a4dcb..834ed2f 100644
--- a/services/api/current.txt
+++ b/services/api/current.txt
@@ -76,6 +76,7 @@
     method @Nullable public String getSdkLibraryName();
     method @NonNull public java.util.List<com.android.server.pm.pkg.AndroidPackageSplit> getSplits();
     method @Nullable public String getStaticSharedLibraryName();
+    method @NonNull public java.util.UUID getStorageUuid();
     method public int getTargetSdkVersion();
     method public boolean isDebuggable();
     method public boolean isIsolatedSplitLoading();