Use Libadalang build-in functionality

[DamDC91]

why not use https://github.com/cwi-swat/ada-air/blob/e4506fef724e8cbf30ef1600c67488a84dd0716f/test/lal-type-hierarchy/src/utils.adb#L35-L36 instead of

Rejuvenation-Ada/src/rejuvenation-finder.adb

Lines 19 to 30 in 6784214

	function Find
	(Node : Ada_Node'Class; Node_Kind : Ada_Node_Kind_Type)
	return Node_List.Vector
	is
	function Predicate (Node : Ada_Node'Class) return Boolean;
	function Predicate (Node : Ada_Node'Class) return Boolean is
	begin
	return Node.Kind = Node_Kind;
	end Predicate;
	begin
	return Find_Predicate (Node, Predicate'Access, Into);
	end Find;

[pjljvandelaar]

Needs some investigation:

1. Should we use a While Next (Node) loop or the Consume function?
2. What are all locations where we could / should use Libadalang.Iterators.Ada_Node_Predicate instead of proprietary instances?