[Ada] New No_Local_Tagged_Types restriction

[Ada] New No_Local_Tagged_Types restriction

Add new configuration restriction No_Local_Tagged_Types. This new
restriction ensures at compile time that all tagged types are only
declared at the library level.

gcc/ada/

	* libgnat/s-rident.ads (Restriction_Id): Add
	No_Local_Tagged_Types, update comment for adding new GNAT
	specific restriction.
	* restrict.ads (Implementation_Restriction): Add
	No_Local_Tagged_Types.
	* sem_ch3.adb (Analyze_Full_Type_Declaration): Add check for
	tagged type at library level.
	* doc/gnat_rm/standard_and_implementation_defined_restrictions.rst:
	Add No_Local_Tagged_Types description.
	* gnat_rm.texi: Regenerate.