Bigint equality is missing

[Fahrrader]

std.primitiveEquals is missing implementation for two bigints. That means,

std.bigint('0') == std.bigint('0')
// false

However, as std.__compare IS implemented for the two, a temporary solution will be:

local bigintEq(a, b) = a >= b && a <= b;
bigintEq(std.bigint('0'), std.bigint('0'))
// true