Support external modules

[itaisteinherz]

First of all, I wanted to thank @GitSquared for making eDEX-UI 👍🏻
The app is really cool, and I have a suggestion that I think could make it even better.

I see the UI as a collection of modules / plugins that are currently hard-coded into the project, and I think there should be a way for users to develop and use their own modules. For example, I could make a Home Assistant module to control my smart appliances, or a Git module to have a Git GUI built into the UI. This would make the app extremely extensible and useful for many different use-cases.

Let me know what you think about the idea.