PackedVectorArray find methods do not specify their test method

**Your Godot version:**
4.0

**Issue description:**
PackedVector2Array and PackedVector3Array do not specify which method they use to test.
Experimentally this is `A == B`, rather than `A.is_equals_approx(B)` but this should be specifically stated.
Being explicit with this saves a lot of headache with people needing to experiment, or read the actual source.

This is likely the same across a lot of things that would be best checked with approximate equality, and so all methods that do equality checking as part of their function should specify if its exact, or approximate equality.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/stable/classes/class_packedvector2array.html#class-packedvector2array-method-find
https://docs.godotengine.org/en/stable/classes/class_packedvector3array.html#class-packedvector3array-method-find