[REQUEST] Add column-widths / column-weights for listview grid layouts

Before opening a feature request

• I checked the next branch to see if the feature has already been implemented
• I searched existing reports to see if it is already requested.

What is the user problem or growth opportunity you want to see solved?

kinda self-explanatory visually ;] i'd like to set arbitrary or automatic width for each column, rather than having all columns having the same size

How do you know that this problem exists today? Why is this important?

afaik we can only define props like listview { columns: 5; spacing: ...; }, but nothing relative to the width of each column

Who will benefit from it?

anyone who wants a similar rofi usage

Rofi version (rofi -v)

Version: 2.0.0-62-g2e7a6c7a (makepkg)

Configuration & Information

https://gist.github.com/awsms/654e6c3927d65d95a6138961fed82d48

Additional information

having tweakable properties like: listview { column-widths: [ 1fr, 3em, 3em, 3em, 3em ]; }

listview { column-weights: [ 8, 1, 1, 1, 1 ]; }

listview { column-weights: [ 60%, 10%, 10%, 10%, 10% ]; }

nth-column

first-column etc. plz lemme know if that's out of scope for rofi :(