Event mode: Enforce reliable hop limit and disallow default public MQTT (#4343)

* Event mode: Enforce reliable hop limit

* Event mode: Short circuit wantsLink on MQTT for default broker address

* Just enforce at channels level since everything uses this

* For events never forward packets with excessive hop_limit

* In EVENT_MODE, don't respond with hop_limit set more then the configured max.

* Correct hop_start when correcting hop_limit in event mode.

* Make EVENT_MODE work from userPrefs.h

* Event mode: Disallow Router or Repeater roles

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Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/mesh/ReliableRouter.cpp

@@ -1,4 +1,5 @@
 #include "ReliableRouter.h"
+#include "Default.h"
 #include "MeshModule.h"
 #include "MeshTypes.h"
 #include "configuration.h"
@@ -17,7 +18,7 @@ ErrorCode ReliableRouter::send(meshtastic_MeshPacket *p)
         // message will rebroadcast.  But asking for hop_limit 0 in that context means the client app has no preference on hop
         // counts and we want this message to get through the whole mesh, so use the default.
         if (p->hop_limit == 0) {
-            p->hop_limit = (config.lora.hop_limit >= HOP_MAX) ? HOP_MAX : config.lora.hop_limit;
+            p->hop_limit = Default::getConfiguredOrDefaultHopLimit(config.lora.hop_limit);
         }
 
         auto copy = packetPool.allocCopy(*p);