Ability to select which config file to use for simulation

[radu-stefan-dt]

Summary
Users should be able to use any monitoring configuration file when running simulations on their extension.

Current vs. Expected Behavior
Currently a user must have a simulator.json file present in the config folder (except python extensions where the activation.json is detected automatically). In addition, this file is different from a monitoring configuration file as the JSON structure starts one node deep in value attribute of a regular file.

These distinctions make it confusing for working with multiple files and it also means not every config file is suitable for simulation. Instead, the project should handle converting a regular file into something suitable for the simulator. On top, when starting a simulation, the panel should have a dropdown with the config files available so the user can choose whichever one.