feat(util): expose calc() expression API

[kumilingus]

Description

Add isCalcExpression, evalCalcExpression and evalCalcFormula functions to utilities.

Documentation

isCalcExpression()

isCalcExpression(value: any) => boolean

Check if the given value is a calc() expression.
e.g. "calc(w + 100)" is true and "not a formula" is false.

evalCalcExpression()

evalCalcExpression(expression: string, rect: g.PlainRect) => string;

Evaluate all calc() formulas in the given expression.
e.g. "translate(calc(w + 10), 0)" in a rect 100x100 will produce a string '"translate(110, 0)"'.

evalCalcFormula()

evalCalcFormula(formula: string, rect: g.PlainRect) => number;

Evaluate the given calc() formula.
e.g w + 10 in context of a rectangle 100x100 will produce a number 110.