Define modular pipelines with config file

[bpmeek]

Description

As a Kedro user I have always wanted to be able to define modular pipelines in a config file.

Context

I believe that doing so will reduce the likelihood of a user inadvertently impacting a pipeline other than the one intended when making changes to pipeline_registry.

Possible Implementation

I created PR #3904 in the Kedro core repository and @datajoely mentioned it might make more sense to make this a plugin rather than part of Kedro Core, but I'm unsure which directory it would belong in.

Possible Alternatives

@datajoely mentioned a possible alternative here