Add module configuration to jitsi-prosody env file

roles/matrix-jitsi/templates/prosody/env.j2

@@ -25,7 +25,7 @@ XMPP_GUEST_DOMAIN={{ matrix_jitsi_xmpp_guest_domain }}
 XMPP_MUC_DOMAIN={{ matrix_jitsi_xmpp_muc_domain }}
 XMPP_INTERNAL_MUC_DOMAIN={{ matrix_jitsi_xmpp_internal_muc_domain }}
 
-XMPP_MODULES=
+XMPP_MODULES={{ matrix_jitsi_xmpp_modules }}
 XMPP_MUC_MODULES=
 XMPP_INTERNAL_MUC_MODULES=