[Radio] Adjust value limits for mix sources and update UI for LSs, CFs & telem. (#5445)

* [firmware][ARM] Adjust some value limits for mix sources and update editing UI for LSs, CFs, & telem. bars:
    * Increase timer limits to +/-8:59:59 when used with LSs, CFs, & bars;
    * Increase Lua script output limits to +/-30K;
    * Trim limits based on extended limit model setting;
    * Limit TX voltage to 25.5;
    * Limit TX time comparison value to 29:59m;
    * Use proper GVar limits (user-configured), display precision, & unit in LSs & telem. bars;
    * Display timer values properly with hours (instead of mmm:ss).

* [firmware] getTimerString() would fail with times >= 100min if hours weren't shown.

* Fix builds w/out GVars.

radio/src/strhelpers.cpp

@@ -179,6 +179,11 @@ char * getTimerString(char * dest, putstime_t tme, uint8_t hours)
     qr.quot = qr2.rem;
   }
 
+  if (!hours && qr.quot > 99) {
+    *s++ = '0' + (qr.quot / 100);
+    qr.quot = qr.quot % 100;
+  }
+
   *s++ = '0' + (qr.quot / 10);
   *s++ = '0' + (qr.quot % 10);
   *s++ = ':';