Overhaul AABB's documentation

[Mickeon]

Very much related to #69816

This PR almost completely overhauls AABB's class reference documentation, and makes it match the current state of Rect2 and Rect2i.

Some of the documentation is ported 1:1 from Rect2's, but there are notable differences from Rect2:

• Say "bounding box" instead of "rectangle";
  • The current documentation likes to say "AABB" a lot but its quite confusing to imagine.
• Reduce the scale of some examples;
  • With AABB we're usually talking about meters, which can be a lot larger than pixels. And besides, using 2 digits for every value, out of 6...? It's a lot to follow.
• Avoid mentions of "bottom-left-back", "top-right-forward" corners.
  • With 3 dimensions envisioning and writing "bottom-left and back" corner is quite difficult to understand.
• Change parameter names around:
  • For some reason, Rect2 and AABB have different parameter names for some methods (e.g. "b" becomes "with"). Descriptions had to be adjusted accordingly, and they may or may not sound more awkward as a result.

Not everything was copied word-for-word, however.

• Clarify intersect_ray() and intersect_segment(), get_endpoints(), etc.;
• Clarify has_volume:
  • "Returns [code]true[/code] if the [AABB] has a volume" thanks, I guess...
• Aadd an example for all *_axis_* methods;
• Fix misinformation in has_point:
  • "Points on the faces of the AABB are considered included, though float-point precision errors may impact the accuracy of such checks.". Oh the "inaccuracy" excuse.
    

    godot/core/math/aabb.h

    Lines 320 to 328 in 26b1fd0

    	if (p_point.x > position.x + size.x) {
    	return false;
    	}
    	if (p_point.y > position.y + size.y) {
    	return false;
    	}
    	if (p_point.z > position.z + size.z) {
    	return false;
    	}

    
    If that statement were true, these would be >=, not >.

---

Feedback is very, very welcome. Thank you for the support in advance.

[AThousandShips]

Looks great generally! Will take a focused look when I have the time, thank you this is a class that needs some love

[raulsntos]

I have only checked the C# examples.

[Mickeon]

I modified the PR to change encloses after #87118

[AThousandShips]

Style and wording looks good, haven't verified the results

Note for cherry picking:
The encloses code is not applicable without cherry picking the changes to 4.1, e.g.

• [Core] Fix AABB.encloses failing on shared upper bound #87118
• [C#] Fix Encloses failing on shared upper bound for AABB and Rect2(I) #87264

[YuriSizov]

Thanks!

[YuriSizov]

Cherry-picked for 4.2.2.