Move apikeys for configuration.lua to apikeys.lua

[Rogerthis]

I want to get the API keys moved to their own dedicated file, similarly to how it's done here:
https://github.com/zeeyado/assistant.koplugin/blob/main/apikeys.lua.sample

This would simplify the process each time I update the plugin, as I wouldn't have to compare both the old and new configuration.lua files to ensure all the API keys are transferred.

Could the default AI be set here, too?

Is the default set by this: provider = "openai",

Or is the default set by this:

    provider_settings = {
        openai = {
            defalut = true, -- optional, if provider above is not set, will try to find one with `defalut =  true`

Also here, there is a typo in defalut it should be default.

[omer-faruq]

During the update, I think you should do the process in reverse; this will speed it up. So, you can simply check the features section at the very end of the sample file to see if any new variables have been added, and if so, move them to your own file. There's usually no need for anything more than that during an update.

Configuration.lua was designed as a place for the user to write their personal preferences and prompts.

About this provider and the default issue: We may remove one of them so as not to confuse the user; you are right about this. However, since it can be easily updated in settings, I think it doesn't hold much importance.