feat: add `ModemPreset.LONG_MODERATE` string name

https://github.com/meshtastic/firmware/pull/2400

app/src/main/java/com/geeksville/mesh/model/Channel.kt

@@ -52,6 +52,7 @@ data class Channel(
                 ModemPreset.MEDIUM_SLOW -> "MediumSlow"
                 ModemPreset.LONG_FAST -> "LongFast"
                 ModemPreset.LONG_SLOW -> "LongSlow"
+                ModemPreset.LONG_MODERATE -> "LongMod"
                 ModemPreset.VERY_LONG_SLOW -> "VLongSlow"
                 else -> "Invalid"
             }