Enhancement: custom start and end of tmux status bar options

[sollymay]

Describe the feature you'd like

Would be awesome to allow start and end of bar variables so that the style matches my current zsh style and neovim bubble styles.

Describe risks you've considered

Probably setting sane defaults as empty strings can help avoid any issues?

Describe alternatives you've considered

I have considered just creating a fork for myself, but I believe this feature is something that will allow Dracula tmux theme to be more flexible (allowing you to set your starting and ending character lets you create more customized status bars