Add clamp, min, max to css-utils

[jacobrask]

Typing out

import { calc } from '@vanilla-extract/css-utils';

width: `clamp(${minValue}, ${someValue}, calc.add(var(--some-var), '1rem'))`

is error prone since there's no syntax validation inside the template string.

import { calc, clamp } from '@vanilla-extract/css-utils';

width: clamp(minValue, someValue, calc.add('var(--some-var)', '1rem'))

is much nicer. Would you accept a PR adding the other CSS math functions to css-utils?

It could also be chainable with calc

width: calc.add('var(--some-var)', '1rem').clamp(minValue, maxValue)
width: calc.add('var(--some-var)', '1rem').min(minValue)
width: calc.add('var(--some-var)', '1rem').max(maxValue)

[mattcompiles]

Happy to accept a PR for this mate. 👍