Add streaming command support.

[wrouesnel]

Implements #250. Add options

• stream-stdout-in-response
• stream-stdout-in-response-on-error
• stream-command-kill-grace-period-seconds

to allow defining webhooks which dynamically stream large content back to the requestor. This allows the creation of download endpoints from scripts, i.e. running a git archive command or a database dump from a docker container, without needing to buffer up the original.

Notes

This includes a refactor and clean up hookHandler to be somewhat more linear then the original was due to the added complexity of handling the deferred behavior of command streaming.

[adnanh]

Nice, I'll have to take some time to review the refactor changes you made to the hookHandler.

[gdubicki]

We have approval, so can we have it merged, @adnanh @wrouesnel ?

[wrouesnel]

A long overdue rebase and merge!

[VojtechMyslivec]

I would really appreciate this feature in CI/CD. Is it possible to review and merge this, since it seems to be implemented already :pray:

Thanks a lot for your work :+1:

[Jackenmen]

I don't know if Adnan will be looking at this any time soon but just as an FYI for the PR author, this is now conflicting again.