Convert the json localization file to arb

Also added a script to combine all the keys. The arb which we get from
poeditor have multiple objects.

scripts/convert_arb_keys.dart

@@ -0,0 +1,47 @@
+#!/usr/bin/env dart
+// SPDX-FileCopyrightText: 2019-2021 Vishesh Handa <me@vhanda.in>
+//
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+// ignore_for_file: avoid_print
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+Future<int> main(List<String> args) async {
+  var contents = await File(args[0]).readAsString();
+  var ds = json.decode(contents);
+  process([], ds);
+  print(json.encode(newMap));
+
+  return 0;
+}
+
+Map<String, String> newMap = {};
+
+void process(List<String> prefixes, Map<String, dynamic> map) {
+  for (var entry in map.entries) {
+    var p = [...prefixes, entry.key];
+
+    if (entry.value is String) {
+      newMap[toCamel(p)] = entry.value;
+      continue;
+    }
+
+    assert(entry.value is Map);
+    process(p, entry.value);
+  }
+}
+
+String toCamel(List<String> l) {
+  var str = l[0].toLowerCase();
+  for (var i = 1; i < l.length; i++) {
+    var s = l[i].toLowerCase();
+    s = s.replaceRange(0, 1, s[0].toUpperCase());
+    // ignore: use_string_buffers
+    str += s;
+  }
+
+  return str;
+}