schema: Add schema for '<inactiveDomain>' element used in the snapshot definition

The '<inactiveDomain>' element stores the next-start definition of a VM
on snapshot. It was not covered by the schema when it was introduced.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2121276
Fixes: 152c165d34
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

src/conf/schemas/domaincommon.rng

@@ -37,6 +37,13 @@
     </element>
   </define>
 
+  <!-- this element is used as a child of a snapshot definition -->
+  <define name="inactiveDomain">
+    <element name="inactiveDomain">
+      <ref name="domaincontents"/>
+    </element>
+  </define>
+
   <define name="domaincontents">
     <ref name="hvs"/>
     <interleave>

src/conf/schemas/domainsnapshot.rng

@@ -83,6 +83,11 @@
             </grammar>
           </choice>
         </optional>
+        <optional>
+          <grammar>
+            <include href="inactiveDomain.rng"/>
+          </grammar>
+        </optional>
         <optional>
           <element name="parent">
             <element name="name">

src/conf/schemas/inactiveDomain.rng

@@ -0,0 +1,10 @@
+<?xml version="1.0"?>
+<grammar xmlns="http://relaxng.org/ns/structure/1.0" datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes">
+  <!-- inactiveDomain element grammar is included into domainsnapshot.rng -->
+  <start>
+    <ref name="inactiveDomain"/>
+  </start>
+
+  <include href="domainoverrides.rng"/>
+
+</grammar>

src/conf/schemas/meson.build

@@ -10,6 +10,7 @@ schema_files = [
   'domain.rng',
   'domainoverrides.rng',
   'domainsnapshot.rng',
+  'inactiveDomain.rng',
   'interface.rng',
   'networkcommon.rng',
   'networkport.rng',