[ACTION] Slack message action edits

[malexanderlim]

Split Slack - Send Message into two distinct actions to support Connect use cases:

• Slack - Send Message to Channel
• Slack - Send Message to User or Group (users as string array, so that you can select one, or multiple)

Remove channelType prop.

[vunguyenhung]

Hi everyone, all test cases are passed! Ready for release!

Test report
https://vunguyenhung.notion.site/ACTION-Slack-message-action-edits-137bf548bb5e814db2f0d41735db491f