add slack integration

[Soypete]

there is currently a workflow to post tweets via discord. We should have a similar workflow that posts tweets via a slack command. we want the content of the tweet to post in a related slack channel as well. There should also be a slack channel where we can track tweet statuses

• add slack command
• accept parameters for text, links, slack channel, etc
• connect slack command to twitter bot
• cross post content from tweet on slack channel and discord channel