feat: replace disableEveryone with disableMentions (#3830)

* add ClientOptions#disableMentions and MessageOptions#disableMentions

* provide tests

* don't sanitize controlled mentions

* add @here mentions to tests

* fix indents (6 spaces instead of 8)

* add Util#cleanContent tests

* add typings for removeMentions

* replace @ with @\u200b AFTER cleaning content as suggested instead of using removeMentions

* better explanation of this option

* no newline in Util.removeMentions

* fix long line

* remove double space

* remove comments (change has been reverted)

* Use Util.removeMentions to remove mentions

* use Util.removeMentions in Util.cleanContent

test/disableMentions.js

@@ -0,0 +1,47 @@
+const Discord = require('../src');
+const { Util } = Discord;
+const { token, prefix } = require('./auth');
+
+const client = new Discord.Client({
+    // To see a difference, comment out disableMentions and run the same tests using disableEveryone
+    // You will notice that all messages will mention @everyone
+    //disableEveryone: true
+    disableMentions: true
+});
+
+const tests = [
+    // Test 1
+    // See https://github.com/discordapp/discord-api-docs/issues/1189
+    '@\u202eeveryone @\u202ehere',
+
+    // Test 2
+    // See https://github.com/discordapp/discord-api-docs/issues/1241
+    // TL;DR: Characters like \u0300 will only be stripped if more than 299 are present
+    '\u0300@'.repeat(150) + '@\u0300everyone @\u0300here',
+
+    // Test 3
+    // Normal @everyone/@here mention
+    '@everyone @here',
+];
+
+
+
+client.on('ready', () => console.log('Ready!'));
+
+client.on('message', message => {
+    // Check if message starts with prefix
+    if (!message.content.startsWith(prefix)) return;
+    const [command, ...args] = message.content.substr(prefix.length).split(' ');
+    
+    // Clean content and log each character
+    console.log(Util.cleanContent(args.join(' '), message).split(''));
+
+    if (command === 'test1')
+        message.reply(tests[0]);
+    else if (command === 'test2')
+        message.reply(tests[1]);
+    else if (command === 'test3')
+        message.reply(tests[2]);
+});
+
+client.login(token).catch(console.error);