feature: align center and spread out first

[nguyentritai2906]

Did you check the docs?

• [X] I have read all the which-key.nvim docs

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

As mentioned in #752 align center is no longer in use and also when keymaps are listed it's not spread out first but instead try to fill the columns first. How can we customize the layout like this in modern preset?

Describe the solution you'd like

Keys are spread horizontally first then column in center of pop up

Describe alternatives you've considered

None

Additional context

No response