add an option to set the keep_alive parameter for Ollama

[sammyf]

Describe the need of your request

ollama has an option keep_alive which determines after how much time of inactivity a model is unloaded (-1 means never unload, 0 means unload now, everything about 0 is the amount of minutes.). It would be nice to be able to set that in the codeGPT options, as reloading the models takes a lot of time.

Proposed solution

add an text box in the ollama specific options to set the keep_alive value, and send it to the server in the API calls.

Additional context

No response