Initial setup for standalone chat with Preact.

- set up standalone static page and message related components
- start separating out css into smaller more manageable files
- start separating out utils into smaller modular files
- renaming some files for consistency

webroot/js/utils/chat.js

@@ -0,0 +1,7 @@
+export const KEY_USERNAME = 'owncast_username';
+export const KEY_AVATAR = 'owncast_avatar';
+export const KEY_CHAT_DISPLAYED = 'owncast_chat';
+export const KEY_CHAT_FIRST_MESSAGE_SENT = 'owncast_first_message_sent';
+export const CHAT_INITIAL_PLACEHOLDER_TEXT = 'Type here to chat, no account necessary.';
+export const CHAT_PLACEHOLDER_TEXT = 'Message';
+export const CHAT_PLACEHOLDER_OFFLINE = 'Chat is offline.';