Implement ApproxEq for all primitives

[WaDelma]

Currently only f32 and f64 are implemented.

• (T, ..)
• [T]
• RefCell<T>
• Cell<T>
• [T; n] (up to 32)

[brendanzab]

We should write down a list of these!

[brendanzab]

Added some to the list!

[sebcrozet]

I think @WaDelma was referring to other numeric primitive types like u32, i32, etc.
Though I'm not sure what ulps would mean for them so it might not be worth it.

[brendanzab]

Hmm, yeah. Is this a problem with the API? What does approx mean for integers?

[milibopp]

What about [T; n]? Could we add it to the list? Maybe up to n = 32 like it's done in std.

[Darkdragon84]

Hey! What's the status on tuples? I would find that very useful for lots and lots of my unit tests.