flatpak: Allow dual installation of app bundles

Part of https://gitlab.gnome.org/GNOME/Initiatives/issues/1.
Allows for the installation of development bundles alongside
stable versions.

Related to https://gitlab.gnome.org/GNOME/gnome-calendar/issues/285

data/appdata/meson.build

@@ -1,9 +1,13 @@
-info = 'org.gnome.Calendar.appdata.xml'
-
-i18n.merge_file(
-  info,
-  input: 'org.gnome.Calendar.appdata.xml.in',
-  output: info,
+appdata_conf = configuration_data()
+appdata_conf.set('appid', application_id)
+appdata = i18n.merge_file(
+  'appdata',
+  input: configure_file(
+    input: files('org.gnome.Calendar.appdata.xml.in.in'),
+    output: 'org.gnome.Calendar.appdata.xml.in',
+    configuration: appdata_conf
+  ),
+  output: '@0@.appdata.xml'.format(application_id),
   po_dir: po_dir,
   install: true,
   install_dir: join_paths(calendar_datadir, 'metainfo')

data/appdata/org.gnome.Calendar.appdata.xml.in.in

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- Copyright 2014 Igor Gnatenko <ignatenko@src.gnome.org> -->
 <component type="desktop">
-  <id>org.gnome.Calendar.desktop</id>
+  <id>@appid@</id>
   <metadata_license>CC0-1.0</metadata_license>
   <project_license>GPL-3.0-or-later</project_license>
   <name>Calendar</name>