Ada: Rework implementation of Ada.Containers.Bounded_Indefinite_Holders

Ada: Rework implementation of Ada.Containers.Bounded_Indefinite_Holders

In particular, this adds support for the case where the Element_Type actual
parameter is a class-wide type.

gcc/ada/
	PR ada/124016
	* doc/gnat_rm/implementation_defined_attributes.rst: Document
	that Finalization_Size attribute is defined for class-wide types.
	* exp_attr.adb (Expand_N_Attribute_Reference) <Finalization_Size>:
	Add support for class-wide types.
	<Size>: Raise Constraint_Error for class-wide types.
	* exp_imgv.adb (Expand_Image_Attribute): Adjust call to renaming.
	(Expand_Wide_Image_Attribute): Likewise.
	(Expand_Wide_Wide_Image_Attribute): Likewise.
	* sem_attr.ads (Finalization_Size): Update comment.
	* sem_attr.adb (Analyze_Image): Adjust call to renaming.
	(Analyze_Attribute): Remove check disallowing Finalization_Size
	attribute for class-wide types.
	* sem_util.ads (Is_Object_Image): Rename into...
	(Is_Object_Prefix): ...this.
	* sem_util.adb (Is_Object_Image): Rename into...
	(Is_Object_Prefix): ...this.
	* libgnat/a-cbinho.ads (Extra_Storage): Use Descriptor_Size and
	Finalization_Size attributes.
	(Max_Allocation_Overhead_In_Storage_Elements): Delete.