Feature Request: Allow sending multiple messages at once

[oilers]

Description

We generate workflow summaries from GHA and format each job as a Block, then post them to a notification channel for job status notifications. Recently, we encountered an issue where some workflows had more than 50 jobs. This exceeds the maximum number of blocks we can post at once. That is reasonable, and our solution is to generate multiple messages and post them in a thread. We do not always know how many messages we must submit since the summary is performed in a shared workflow. In order to do this I am left with 3 bad options:

1. Send each message as part of a matrix job; this means each message consumes a self-hosted ARC runner, which seems excessive
2. Fork the action ourselves and add support
3. Do not use the action and fall back to making API calls ourselves

It would be great if there were some way of passing in multiple messages.

What type of issue is this? (place an x in one of the [ ])

• [ ] bug
• [x] enhancement (feature request)
• [ ] question
• [ ] documentation related
• [ ] example code related
• [ ] testing related
• [ ] discussion

Requirements (place an x in each of the [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.
• [x] I've searched for any related issues and avoided creating a duplicate issue.