Require custom permission for non-Microdroid

Running with an os other than "microdroid" should require the
USE_CUSTOM_CONFIG permissions (as do our other @TestApi).

Add check, fix up tests.

Bug: 323513087
Test: atest MicrodroidTestApp MicrodroidHostTestCases
Change-Id: If7bc577b275f2a55c80c302ed00d5947676daa6a
diff --git a/javalib/api/test-current.txt b/javalib/api/test-current.txt
index 0a988d8..36a82f7 100644
--- a/javalib/api/test-current.txt
+++ b/javalib/api/test-current.txt
@@ -16,7 +16,7 @@
 
   public static final class VirtualMachineConfig.Builder {
     method @FlaggedApi("com.android.system.virtualmachine.flags.avf_v_test_apis") @NonNull public android.system.virtualmachine.VirtualMachineConfig.Builder addExtraApk(@NonNull String);
-    method @FlaggedApi("com.android.system.virtualmachine.flags.avf_v_test_apis") @NonNull public android.system.virtualmachine.VirtualMachineConfig.Builder setOs(@NonNull String);
+    method @FlaggedApi("com.android.system.virtualmachine.flags.avf_v_test_apis") @NonNull @RequiresPermission(android.system.virtualmachine.VirtualMachine.USE_CUSTOM_VIRTUAL_MACHINE_PERMISSION) public android.system.virtualmachine.VirtualMachineConfig.Builder setOs(@NonNull String);
     method @NonNull @RequiresPermission(android.system.virtualmachine.VirtualMachine.USE_CUSTOM_VIRTUAL_MACHINE_PERMISSION) public android.system.virtualmachine.VirtualMachineConfig.Builder setPayloadConfigPath(@NonNull String);
     method @FlaggedApi("com.android.system.virtualmachine.flags.avf_v_test_apis") @NonNull @RequiresPermission(android.system.virtualmachine.VirtualMachine.USE_CUSTOM_VIRTUAL_MACHINE_PERMISSION) public android.system.virtualmachine.VirtualMachineConfig.Builder setVendorDiskImage(@NonNull java.io.File);
     method @NonNull public android.system.virtualmachine.VirtualMachineConfig.Builder setVmConsoleInputSupported(boolean);
diff --git a/javalib/src/android/system/virtualmachine/VirtualMachineConfig.java b/javalib/src/android/system/virtualmachine/VirtualMachineConfig.java
index 3e5e2f7..144989e 100644
--- a/javalib/src/android/system/virtualmachine/VirtualMachineConfig.java
+++ b/javalib/src/android/system/virtualmachine/VirtualMachineConfig.java
@@ -1024,6 +1024,7 @@
          */
         @TestApi
         @FlaggedApi(Flags.FLAG_AVF_V_TEST_APIS)
+        @RequiresPermission(VirtualMachine.USE_CUSTOM_VIRTUAL_MACHINE_PERMISSION)
         @NonNull
         public Builder setOs(@NonNull String os) {
             mOs = requireNonNull(os, "os must not be null");