Add optimized is_in_half_space_identity, contains_aabb_identity, and intersects_obb_identity

[Saratii]

Objective

This adds an optimized version of is_in_half_space, Frustum::contains_aabb_identity, Aabb::is_in_half_space_identity, and Frustum::intersects_obb_identity that takes advantage of how calling with IDENTITY (common) reduces the amount of matrix multiplications.

Solution

Add a specialized function without touching the original that assumes Identity was passed to simplify math.

Testing

I use this function extensively in my own project. I asserted the old function called with identity always returns the same as my new function.
I bench marked and profiled the usage in my real application and noticed a 16% speed up on Linux and 20% on windows for contains_aabb.
I bench marked intersects_obb_identity and noticed a 39% increase on linux and 38% on windows.
Both functions have unit tests that assert calling with identity yields the same result in both versions.

[Saratii]

Please squash commits, I see no button to do so.

[alice-i-cecile]

I like this! Before I approve, can you check if we can get the same performance improvements by using const if branching on the existing methods?

If that fails, please:

1. Add doc links to these methods from the unspecialized versions.
2. Add true doc links back to the unspecialized versions.
3. Add some basic tests asserting equivalence.

[alice-i-cecile]

Please squash commits, I see no button to do so.

We always squash on merge: don't worry about it for this project :)

[Saratii]

@alice-i-cecile 38% increase on windows and 39% increase on linux with a similar identity fn for intersects_obb. intersects_obb also seems to be more heavily used and heavier to compute. I would appreciate another code review :)