Allow custom DroneModels.json to be loaded at runtime

[mkrupczak3]

Description:

Currently, the DroneModels JSON file is hard-coded into the app and is not user-configurable. While it has data for many drone models, it is conceivable that users may find their particular drone is unsupported. In addition, some users of proprietary drones may not be permitted by their workplace to share details of their drone with this project.

The program should let a user load their own custom JSON file so that they can configure and add support for their own particular drone model

User Story

As a User, I want to load a DroneModels JSON file, so that I can use my drone with the app

[mkrupczak3]

I'm kind of conflicted about whether to implement this feature.

On the one hand, it makes testing easier, allowing the user to tweak their camera parameter values to find the values with best accuracy.

A significant drawback however is that it may discourage users from contributing their values back to the DroneModels upstream