Refactor: Slack Message

[abidishajia]

We currently have a Slack folder with a sendMessage function. It is used for the elex-testing-calendar bot.

• Move the Slack folder to the root directory.
• Refactor the code to pass the message as an argument and use the function for both the bots.
• For the elex-tabulation-data bot, only send a message to the channel when there is an update. The format could be something like:
• The race call status for X, Y, and Z races have changed to Called.
• The tabulation status for X, Y, and Z has been changed to Active Tabulation.

[abidishajia]

Since the notifications for tabulationStatus and raceCallStatus are very complex, it is best to leave them separate. Maybe the other way would be to format a message in different files, and then just pass in the message as an argument instead of the actual data.