feature: Fine-tune italics settings support

[pithecantrope]

Did you check the documentation and existing issues?

• I have read all the midnight.nvim documentation
• I have searched through all existing issues of midnight.nvim

Is your feature request related to a problem? Please describe.

I program in C and want italic keywords. How to achieve that?

Describe the solution you'd like

Would be nice to just: highlight_groups = { keywords = { italic = true } }

Describe alternatives you've considered

Fine-tune bold would be nice too

Additional context

(Awesome color scheme btw)

[dasupradyumna]

Thank you for the suggestion. I am sorry for the late response ; I have been busy with my day-job.
I will be working on making some configuration changes to this colorscheme soon!