Update language_color_generator

- refactor code
- generate const map
- move to /tool directory

Author: kevmoo

lib/src/const/language_color.dart

@@ -0,0 +1,39 @@
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:yaml/yaml.dart';
+
+const _indent = '  ';
+const _path = './lib/src/const/language_color.dart';
+const _url = 'https://raw.githubusercontent.com/'
+    'github/linguist/master/lib/linguist/languages.yml';
+
+Future main() async {
+  var response = await http.Client().get(_url);
+
+  var yaml = loadYaml(response.body) as YamlMap;
+  var stringBuffer = StringBuffer()
+    ..writeln('// GENERATED CODE - DO NOT MODIFY BY HAND')
+    ..writeln('// VERSION OF ${DateTime.now().toIso8601String()}')
+    ..writeln()
+    ..writeln('const languagesColor = <String, String>{');
+
+  var map = yaml.value as YamlMap;
+  var languages = map.keys.cast<String>().toList(growable: false)..sort();
+
+  for (var language in languages) {
+    var color = map[language]['color']?.toString()?.toUpperCase() ?? '#000000';
+
+    language = language.replaceAll("'", "\\'");
+
+    stringBuffer.writeln("$_indent'$language': '$color',");
+  }
+
+  stringBuffer.writeln('};');
+
+  File(_path)
+    ..createSync()
+    ..writeAsStringSync(stringBuffer.toString());
+
+  print('File created with success');
+}