[Cousine Nerd Font] Adding round borderchars.


- [X] I have searched the [issues](https://github.com/ryanoasis/nerd-fonts/issues) for my request and found nothing related and/or helpful
- [X] I have searched the [FAQ](https://github.com/ryanoasis/nerd-fonts/wiki/FAQ-and-Troubleshooting) for help
- [X] I have searched the [Wiki](https://github.com/ryanoasis/nerd-fonts/wiki) for help

**Is your feature request related to a problem? Please describe.**
I'm using Cousine Nerd Font for display text and icon for vim terminal also gvim. Today, I worked with some settings with borderchars then I realized that Cousine Nerd Font not support it. I changed to Hack Nerd Font, it can display round borderchars like my expectation.
So I wonder if Cousine Nerd Font can have round borderchars 
`
 '─│─│╭╮╯╰'
`

**Additional context**

https://user-images.githubusercontent.com/75968004/216885210-68367f75-9411-4c14-b9e2-58be74e36a6a.mp4

