Rework config values and add settings GUI

based on #205 (so maybe integrate this into the base PR first or merge this PR instead) solves #235

Rework config values

complete rework of how config values work in MantellaSoftware
All config values are now defined in code, including:
- ID
- Name
- Description
- Value
- Default Value
- Constraints
- IsHidden
- Tags
- OnValueChangeCallback
On start of the software an instance that holds the current value of each config value is generated from the definitions
These instances are filled gracefully by which config values can be loaded from the config.ini
If there is no config.ini a new one will be created from scratch
ConfigLoader loads the config values now from the current values. Any config value that is actually loaded can trigger a constraint violation
Any unsolved constraint violations will block the Mantella HTTP routes for conversation or STT from being used until resolved
A restart of MantellaSoftware is no longer required when changing config values from the GUI

Adds a browser based GUI to MantellaSoftware that uses Gradio
Changes the Flask server to FastAPI/uvicorn to support serving the new HTTP routes for Mantella as well as the Gradio GUI from the same app
- No explicit test done, but the responses feel faster than with Flask