[Batcher] Add ability to send batched http requests to runtime

[rokatyy]

Jira - https://iguazio.atlassian.net/browse/NUC-156 part of https://iguazio.atlassian.net/browse/NUC-146

This PR introduces a new events processing logic. Specifically, it allows the processing of batched events instead of the usual single event processing. For now, we only support this feature for python runtime and http trigger kind.

Batching can be enabled by adding batch configuration to function config.
Example:

batch:
        mode: enable
        batchSize: 1000
        timeout: 1s

[TomerShor]

Some initial comments.
Will batching be supported in all triggers right OOB?

Since we only support it on python runtime for now, I would add a warning log that it is not supported if a different runtime is set (and maybe for triggers that don't support it too (e.g. shell))

[quaark]

Looks really good!
A couple of minor suggestions

[TomerShor]

Awesome stuff!
Added a few comments

[TomerShor]

A bit more to go :)

[TomerShor]

I know it is not you TODO, but do you have an idea what does it mean?

[rokatyy]

@TomerShor No, but I can assume that it is only relevant for normal flow with single event processing, because in that case we use pre-defined events to wrap the context