feat: Add extra template arguments option

[alexifm]

This is draft to propose adding an option for passing extra arguments to the jinja templates based on the comment here: #224 (comment)

Still requires tests and formatting/cleanup but feedback on if there is interest in this and it's taking the right approach would be appreciated.

[dbanty]

I'm not totally clear on what the use-case is for kwargs like that? They're effectively hard-coded values, so why not just include them in the custom template you're using? I assume there's just something here I'm missing 😅.

If we were to do this, I think it makes more sense to put it in the config file since you could use YAML/JSON object notation instead of us having to parse from command line. That sort of depends on how these would be used though I guess.

[dbanty]

Closing since this is kind of stale, but happy to revisit the idea at some point if this is needed.