Add tech design docs for feature that allows Rails to poke remote dev module

What is this MR about

This MR outlines the technical changes required to implement the requirements mentioned here

The purpose of sharing this draft is

• to get some early feedback on the direction being taken
• gather some thoughts and opinions on which solution can be followed to deal with the leader node communication issue

PS: Since this is a tech design of a feature, I wasn't sure if putting it in under docs/ directly was the right thing to do. So I've taken the liberty to create a folder docs/tech-designs for this doc. My idea was that once this feature is released we can just extract the key information relevant to the architecture and add them to the main architecture docs, which still preserving this doc as the SSOT of the technical decisions made for the feature. But feel free to correct me here or share any other suggestions.