Implement API key reset option

[TheR1D]

Implement an option to reset an API key using command line argument --reset-key. When user provides this flag delete file located in ~/.config/shell-gpt/api_key.txt and ask for new API key. Additionally impement API key validation. Since OpenAI doesn't have dedicated endpoint just for key validation, call https://api.openai.com/v1/completions with some test prompt, make sure response status code is not 403, if so, ask user for valid API key.

[highonweb]

Hey I messed up and I pasted my API key twice, do you need help with this feature

[TheR1D]

@highonweb solution for now: #5

[highonweb]

Thanks bro. Got it

[berkott]

I've been working on a PR with this that I'll try to make a PR for within the next week.

[m4l490n]

@highonweb solution for now: #5

That doesn't work. There is no .config/shell-gpt/api_key.txt and reinstalling doesn't work for having shell-gpt ask for the key again. I can't make it ask for the key again.