engineering: mark metapackages with @META suffix

pkg.in/lists/engineering/2d-cad

 # 2D CAD (Computer Aided Design)
-engineering-2D-CAD
+engineering-2D-CAD@META

pkg.in/lists/engineering/3d-cad

 # 3D CAD (Computer Aided Design)
-engineering-3D-CAD
+engineering-3D-CAD@META

pkg.in/lists/engineering/3d-printer

 # 3D Printer Software
-engineering-3D-printing
+engineering-3D-printing@META

pkg.in/lists/engineering/apcs

 # Advanced Process Control Software
-engineering-APCS
+engineering-APCS@META

pkg.in/lists/engineering/cam

 # CAM (Computer-aided manufacturing)
 # and G-Code generators
-engineering-CAM
+engineering-CAM@META

pkg.in/lists/engineering/cnc

 # CNC (Computer Numerical Control)
-engineering-CNC
+engineering-CNC@META

pkg.in/lists/engineering/eda

 # EDA (Electronic Design Automation)
-engineering-EDA
+engineering-EDA@META

pkg.in/lists/engineering/misc

-engineering-misc
+engineering-misc@META