Configurable separator characters.

[Arelav]

Thanks for so great Tmux plugin.
It would be nice to have a variable to provide separator charchers to make it more configurable.
I'll add few self-explanatory images.

[arcticicestudio]

Hi @Arelav 👋, thanks for your contribution 👍

The default status bar content is an optional feature of this theme, but making it more flexible is always a good idea.
This could be done by adding new theme configurations, i.e. see #61 which allows users to set a custom date format through the @nord_tmux_date_format variable.
Adding pre-defined glyphs is not the way to go but allowing users to either set the glyph itself or the Unicode ID.

I'll add this to the backlog so that everyone is free to submit a PR.

[Arelav]

I was thinking passing the gliph as a string is most flexible and simple to implement.