Canned Messages via InkHUD menu (#7096)

* Allow observers to respond to AdminMessage requests
Ground work for CannedMessage getters and setters

* Enable CannedMessage config in apps for InkHUD devices

* Migrate the InkHUD::Events AdminModule observer
Use the new AdminModule_ObserverData struct

* Bare-bones NicheGraphics util to access canned messages
Handles loading and parsing. Handle admin messages for setting and getting.

* Send canned messages via on-screen menu

* Change ThreadedMessageApplet from Observer to Module API
Allows us to intercept locally generated packets ('loopbackOK = true'), to handle outgoing canned messages.

* Fix: crash getting empty canned message string via Client API

* Move file into Utils subdir

* Move an include statement from .cpp to .h

* Limit strncpy size of dest, not source
Wasn't critical in ths specific case, but definitely a mistake.

src/graphics/Screen.cpp

@@ -58,7 +58,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "mesh/Channels.h"
 #include "mesh/generated/meshtastic/deviceonly.pb.h"
 #include "meshUtils.h"
-#include "modules/AdminModule.h"
 #include "modules/ExternalNotificationModule.h"
 #include "modules/TextMessageModule.h"
 #include "modules/WaypointModule.h"
@@ -1377,12 +1376,13 @@ int Screen::handleInputEvent(const InputEvent *event)
     return 0;
 }
 
-int Screen::handleAdminMessage(const meshtastic_AdminMessage *arg)
+int Screen::handleAdminMessage(AdminModule_ObserverData *arg)
 {
-    switch (arg->which_payload_variant) {
+    switch (arg->request->which_payload_variant) {
     // Node removed manually (i.e. via app)
     case meshtastic_AdminMessage_remove_by_nodenum_tag:
         setFrames(FOCUS_PRESERVE);
+        *arg->result = AdminMessageHandleResult::HANDLED;
         break;
 
     // Default no-op, in case the admin message observable gets used by other classes in future