Add option for make lightline mode in bold

[fitrh]

I'm new in vim configuration stuff, so i don't know how to make it as a part of tokyonight option, for now, if i want vim mode to bold, i have to modified lightline file like

let s:p.normal.left = [ [ s:normal_l1_fg, s:normal_l1_bg, 'bold' ], [ s:normal_l2_fg, s:normal_l2_bg ] ]

I think it's nice to have them as an option in theme.

This is how vim mode look like

And this is with bold