Refactor messages tab UI

lib/utils/location_formats.dart

@@ -0,0 +1,25 @@
+String formatPlusCode(double lat, double lon) {
+  const base = '23456789CFGHJMPQRVWX';
+
+  var normalizedLat = (lat + 90) / 180;
+  var normalizedLon = (lon + 180) / 360;
+
+  final buffer = StringBuffer();
+  for (var i = 0; i < 8; i++) {
+    if (i == 4) {
+      buffer.write('+');
+    }
+
+    final latDigit = (normalizedLat * 20).floor() % 20;
+    final lonDigit = (normalizedLon * 20).floor() % 20;
+
+    buffer
+      ..write(base[latDigit])
+      ..write(base[lonDigit]);
+
+    normalizedLat = (normalizedLat * 20) % 1;
+    normalizedLon = (normalizedLon * 20) % 1;
+  }
+
+  return buffer.toString();
+}