Add rotate_toward method to Vector2, Vector3, Quaternion, and Basis

[fire]

Trial pr to implement godotengine/godot-proposals#7965

[ettiSurreal]

Vector functions with separate magnitude move taken out.

	_FORCE_INLINE_ Vector2 rotate_toward(Vector2 p_to, real_t p_delta) {

		if (Math::is_zero_approx(p_rotation_delta)) {
			return *this;
		}

		if (p_delta < 0.0f) {
			p_delta = -p_delta;
			p_to = -p_to;
		}

		real_t angle = angle_to(p_to);

		if (angle < p_delta) {
			return p_to;
		}

		return slerp(p_to, p_delta / angle);
	}

	_FORCE_INLINE_ Vector3 rotate_toward(Vector3 p_to, float p_delta) {

		if (Math::is_zero_approx(p_delta)) {
			return *this;
		}

		if (p_delta < 0.0f) {
			p_delta = -p_delta;
			p_to = -p_to;
		}

		float angle = angle_to(p_to);

		if (angle < p_delta) {
			return p_to;
		}

		return slerp(p_to, p_delta / angle);
	}

[ettiSurreal]

@fire you mentioned on the chat (before I left the reviews yesterday) that you are abandoning this PR and were hoping the original author (I assume referring to me) would be able to take it on. I am supposed to make my own PR on this right?

[AThousandShips]

Suggested change

	_FORCE_INLINE_ Basis rotate_toward(Basis p_to_basis, real_t p_delta) const {
	_FORCE_INLINE_ Basis rotate_toward(const Basis &p_to_basis, real_t p_delta) const {

[AThousandShips]

Suggested change

	Returns the result of rotating this vector towards [param to], by increment [param delta] (in radians).
	Returns the result of rotating this vector toward [param to], by increment [param delta] (in radians).

"towards" is generally considered UK English, and "toward" is used in the line below so best to keep uniform

[AThousandShips]

Suggested change

	Returns the result of rotating this vector towards [param to], by increment [param delta] (in radians).
	Returns the result of rotating this vector toward [param to], by increment [param delta] (in radians).

[fire]

Superseded by: #82926