chore(codeowners): add frontend files expertise

Signed-off-by: John Molakvoæ <skjnldsv@users.noreply.github.com>

.github/CODEOWNERS

@@ -28,6 +28,13 @@
 /apps/weather_status/appinfo/info.xml         @julien-nc @juliushaertl
 /apps/workflowengine/appinfo/info.xml         @blizzz @juliushaertl
 
+# Frontend expertise
+/apps/files/src                  @skjnldsv
+/apps/files_external/src         @skjnldsv
+/apps/files_reminders/src        @skjnldsv
+/apps/files_sharing/src/actions  @skjnldsv
+/apps/files_trashbin/src         @skjnldsv
+
 # Security team
 /resources/codesigning              @mgallien @miaulalala @nickvergessen
 /resources/config/ca-bundle.crt     @ChristophWurst @miaulalala @nickvergessen