ttrss: Use drop-in config component for /etc files

Tests:

- Config files are all symlinks in /etc/
- Web interface works

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

debian/freedombox.maintscript

@@ -138,3 +138,4 @@ rm_conffile /etc/avahi/services/ssh.service 23.10~
 rm_conffile /etc/apache2/includes/freedombox-single-sign-on.conf 23.10~
 rm_conffile /etc/apache2/conf-available/syncthing-plinth.conf 23.10~
 rm_conffile /etc/apache2/conf-available/transmission-plinth.conf 23.10~
+rm_conffile /etc/apache2/conf-available/tt-rss-plinth.conf 23.10~

plinth/modules/ttrss/__init__.py

@@ -6,6 +6,7 @@ from django.utils.translation import gettext_lazy as _
 
 from plinth import app as app_module
 from plinth import cfg, frontpage, menu
+from plinth.config import DropinConfigs
 from plinth.daemon import Daemon
 from plinth.modules.apache.components import Webserver
 from plinth.modules.backups.components import BackupRestore
@@ -37,7 +38,7 @@ class TTRSSApp(app_module.App):
 
     app_id = 'ttrss'
 
-    _version = 5
+    _version = 6
 
     def __init__(self):
         """Create components for the app."""
@@ -73,6 +74,11 @@ class TTRSSApp(app_module.App):
         ])
         self.add(packages)
 
+        dropin_configs = DropinConfigs('dropin-configs-ttrss', [
+            '/etc/apache2/conf-available/tt-rss-plinth.conf',
+        ])
+        self.add(dropin_configs)
+
         firewall = Firewall('firewall-ttrss', info.name,
                             ports=['http', 'https'], is_external=True)
         self.add(firewall)