Move invite message from Glitch to Camille

[mergesort]

This is the message we've been using currently on Glitch.

SLACK_CODE_OF_CONDUCT_MESSAGE="<http://bit.ly/iosdevslack|To ensure we create and harbor a safe and considerate environment, please read over and accept our code of conduct before getting started.>"

SLACK_WELCOME_MESSAGE="*Welcome to the iOS Folks Slack*"

SLACK_CHANNELS_MESSAGE="We've got plenty of interesting channels, I recommend you take a look around <#C031NHW9G> for the complete list. Just for starters, there are channels on specific topics like <#C03FWU59B>, <#C0G0MMJ69>, <#C0AET0JQ5>, <#C035CBKML>, <#C031NHW9L>, <#C0JCNCX9Q>, and dozens more I haven't mentioned, including platforms like <#C0ACXUQ8L>, <#C035KA57R>, specific tools like <#C0HME659V> or <#C1SLCHYJJ>, and even locations like <#C031TFJL6>, <#C031X1P9Y>, and <#C2YNS1V88>."

SLACK_META_MESSAGE="Discussion about the Slack happens in <#C04CKSRK1>, so if you have any ideas or even think there's a good channel to add, post in there and we'll be happy to further the discussion."

SLACK_OUTRO_MESSAGE="Most importantly, be nice, have fun, and welcome! 👋🏼:"

Sending the messages in this order.

send_intro_message(event, SLACK_WELCOME_MESSAGE);
send_intro_message(event, SLACK_CHANNELS_MESSAGE);
send_intro_message(event, SLACK_META_MESSAGE);
send_intro_message(event, SLACK_OUTRO_MESSAGE);
send_code_of_conduct_message(event);