Enterprise IT: Allow configuration via Windows registry keys

[SommerEngineering]

We should optionally allow configuration via Windows registry keys to enable administrators in enterprises to centrally manage the configuration through group policies. The registry settings should take precedence over those in the configuration file. However, we should not allow settings concerning user interaction via the registry: We do not want administrators to dictate how the software is used. These should only be changeable by the respective user.

Through the registry, settings related to security and privacy, in particular, should be adjustable:

• Are users allowed to connect their email accounts with an LLM?
• Are users allowed to use cloud-based LLMs?
• Is the configuration of custom LLMs allowed at all, or can only predefined LLMs be used?
• Is the app allowed to check for updates and install them?

[SommerEngineering]

See https://github.com/keepassxreboot/keepassxc/issues/2189 and https://github.com/keepassxreboot/keepassxc/pull/11223 for ideas on how to achieve this.