Add table slack_conversation_replies

[ValentinCrr]

Is your feature request related to a problem? Please describe.

As a data analyst in a company using slack as its key communication tool, I want to make statistics by threads (e.g. time between request and last message, nb of replies to a message, etc.)

However, using the slack_search table, I couldn't find a way to group the messages of a single thread (nor to relate the main message to replies in thread).

Describe the solution you'd like
After asking the question on Turbot slack, the idea of creating a new table based on the "conversation.replies" API arose. However, this might not be the only solution. Feel free to propose anything else.

Describe alternatives you've considered
None

Additional context
Documentation of the (current) slack_search table : https://hub.steampipe.io/plugins/turbot/slack/tables/slack_search#inspect