Fix use controlled domain for desktop entry

If the goal of using the reverse DNS notation is to
prevent naming conflicts, then I suppose we should use
a domain nameunder the FPF control.

Caution: I haven't found any other mention of this file name
on GitHub, but I suspect this might be a breaking change?
Search https://github.com/search?q=org%3Afreedomofpress+org.freedomofthepress

securedrop_client/app.py

@@ -43,7 +43,7 @@
 
 DEFAULT_LANGUAGE = LanguageCode("en")
 DEFAULT_SDC_HOME = "~/.securedrop_client"
-DESKTOP_FILE_NAME = "org.freedomofthepress.securedrop.client"
+DESKTOP_FILE_NAME = "press.freedom.securedrop.client"
 ENCODING = "utf-8"
 GETTEXT_DOMAIN = "messages"
 LOGLEVEL = os.environ.get("LOGLEVEL", "info").upper()