Add maintenance as a lazy service

We need to advertise it as a lazy service to allow VS to be started
when it is needed.

To avoid having to have 4 variants of the .rc file, switch from
picking one to constructing it from fragments.

Bug: 294177871
Test: Builds, final .rc is correct
Change-Id: I10faf32249e41cab21a602f94231786f95e20d3d
diff --git a/apex/virtualizationservice.rc.base b/apex/virtualizationservice.rc.base
new file mode 100644
index 0000000..688db10
--- /dev/null
+++ b/apex/virtualizationservice.rc.base
@@ -0,0 +1,21 @@
+# Copyright (C) 2021 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+service virtualizationservice /apex/com.android.virt/bin/virtualizationservice
+    class main
+    user system
+    group system
+    disabled
+    oneshot
+    interface aidl android.system.virtualizationservice