describegpt: add a --prompt-file option

[jqnatividad]

The prompt file is a json file specifying the dictionary prompt, description prompt and the tags prompt to use.

If specified, it will load the prompts from the json file instead of using the default prompts.

[rzmk]

@jqnatividad Is there a default format that's expected for the prompt file? For example:

{
    "dictionary_prompt": "...",
    "description_prompt": "...",
    "tags_prompt": "..."
}

We can then check if the --prompt-file option and relevant inference option(s) are used are used, and if they exist in the file to run them.

Also should we specify that prompt file format anywhere?

[jqnatividad]

@rzmk , add some metadata attributes:

{
  "name": "...",
  "description": "...",
  "author": "...",
  "version": "...",
  "tokens": 10,
  "dictionary_prompt": "...",
  "description_prompt": "..",
  "tags_promt": "..."
}

the tokens attribute will be used unless --max-tokens option is set explicitly when invoking describegpt.

As for specifying the --prompt-file format. document it in the docs directory, similar to how fetch has its own markdown file there.

[rzmk]

@jqnatividad How should we identify where to input the stats, frequency, and json_add string within these prompts?

If we can do this then we could consider moving the current prompt functions into a default prompt file.