refactor: Use variables for button padding, font and weight

[Fumler]

Please tick a box

• refactor (A code change that neither fixes a bug nor adds a feature)

If you're adding a feature, is it documented in a storybook story?

• Yes

Are the components you're working on reusable between brands?

• Yes (Using variables that are defined in the default theme)

[misund]

Interesting approach to nested variables!

[misund]

I like the customization options here! Not so much a fan of that these values are not connected to the rest of the design pattern. I wish we could have both.

[misund]

I realize this is a very vague comment. I'll come back with a stronger opinion tomorrow.

[misund]

I don't think it's a good idea to specify exact sizes for each component in this way. If we apply this approach across the board, the number of settings would grow to a level that's not really maintainable. In short, this solution does not scale well.

Instead, we should calculate the margin and padding of components using horizontalBase and verticalBase.
If a brand has needs that this approach can't accomodate, we should consider creating another component.