feat(Message|TextChannel): Inline replies (#4874)

* feat(Message): remove reply functionality

* feat(InlineReplies): add INLINE_REPLY constant/typing

* feat(InlineReplies): add Message#replyReference property

* feat(InlineReplies): add typings for sending inline replies

* feat(InlineReplies): provide support for inline-replying to messages

* feat(Message): add referencedMessage getter

* fix: check that Message#reference is defined in referencedMessage

* refactor(InlineReplies): rename property, rework Message resolution

* docs: update jsdoc for inline replies

* feat(Message): inline reply method

* fix(ApiMessage): finish renaming replyTo

* fix: jsdocs for Message#referencedMessage

Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>

* fix: restore reply typings

* fix: dont pass channel_id to API when replying

* chore: update jsdocs

* chore: more jsdoc updates

* feat(AllowedMentions): add typings for replied_user

* fix: naming conventions

* fix(Message): referenced_message is null, not undefined

* fix(MessageMentionOptions): repliedUser should be optional

* chore: get this back to the right state

* fix(ApiMessage): pass allowed_mentions when replying without content

* fix(ApiMessage): prevent mutation of client options

Co-authored-by: almostSouji <timoqueezle@gmail.com>
Co-authored-by: Tristan Guichaoua <33934311+tguichaoua@users.noreply.github.com>

docs/examples/avatars.js

@@ -23,7 +23,7 @@ client.on('message', message => {
   // If the message is "what is my avatar"
   if (message.content === 'what is my avatar') {
     // Send the user's avatar URL
-    message.reply(message.author.displayAvatarURL());
+    message.channel.send(message.author.displayAvatarURL());
   }
 });