schema: Use org.gnome prefix and adapt to changes

In preparation to moving to GNOME all the IDs, DBus object paths, etc should
change.

data/meson.build

@@ -68,7 +68,7 @@ install_data(
   )
 )
 
-schema_src = 'sm.puri.Calls.gschema.xml'
+schema_src = 'org.gnome.Calls.gschema.xml'
 compiled = gnome.compile_schemas(build_by_default: true,
                                  depend_files: files(schema_src))
 

data/org.gnome.Calls.gschema.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <schemalist gettext-domain="purism-calls">
-  <schema id="sm.puri.Calls" path="/sm/puri/Calls/">
+  <schema id="org.gnome.Calls" path="/org/gnome/Calls/">
 
     <key name="auto-use-default-origins" type="b">
       <default>true</default>