Idea: new assistant_custom_prompts.lua file

[Rogerthis]

I'd like the custom prompts to be moved to their own dedicated file, similarly to how it's done here:
https://github.com/zeeyado/assistant.koplugin/blob/main/custom_prompts.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 assistant_prompts.lua files to ensure all my prompts are transferred and working properly.

[omer-faruq]

If you keep the modified or new prompts in configuration.lua, you don't need to check assistant_prompt when updating. configuration.lua is designed for this purpose; you can also change the prompt of a built-in button there. That's how I use it.