feat: exposing request from event in interaction handler in order to Ack event with custom payload

[Vladmel1234]

this PR addressing https://github.com/slack-io/slacker/issues/22

[Vladmel1234]

There is no much sense in first commit without the second one

[raed-shomali]

Would love to get @arusso 's opinion on this PR.

[arusso]

I'll fix the workflow error, the line length shouldn't prevent progression.

I'll try and look at this later today. I have questions but need to dig in a bit to make sure they're not self explanatory.

[Vladmel1234]

btw if it is needed to add an example i will happily add one

[raed-shomali]

Examples are always welcome!

[raed-shomali]

@arusso Let us know when you have had the chance to review the PR.