Webform Handler

Problem/Motivation

We needed to create a webform handler to send webform data to a Klaviyo list, and we would like to give it back to the community, so I would like to know what architecture would you prefer for us to open this MR to contribute to the module. Do you prefer a sub-module as the others or just add it to the main module?

Proposed resolution

We'll open an MR with the code that was already created