Fix root project's closure processing

By making sure we include withed aggregated libraries and
extended projects in its closure, to add all the project's
source files at once, no matter where they are coming from.

For eng/ide/ada_language_server#1598

(cherry picked from commit b985804)

Author: AnthonyLeonardoGracio

source/ada/lsp-ada_contexts.adb

@@ -629,24 +629,20 @@ package body LSP.Ada_Contexts is
 
          procedure Process_Closure
            (Root     : GPR2.Project.View.Object;
-            Callback : not null access procedure
-              (View : GPR2.Project.View.Object))
-         is
+            Callback :
+              not null access procedure (View : GPR2.Project.View.Object)) is
          begin
-            --  First process the closure of the view
-            for View of Root.Closure
-              (Include_Self => True) when not View.Is_Runtime
+            --  Process the closure of the root project, including any
+            --  aggregated library and the projects that it might extend.
+            for View
+              of Root.Closure
+                   (Include_Self       => True,
+                    Include_Extended   => True,
+                    Include_Aggregated => True)
+              when not View.Is_Runtime
             loop
                Callback (View);
             end loop;
-
-            --  If we're looking at an extending view, now
-            --  process the closure of the extended views.
-            if Root.Is_Extending then
-               for V of Root.Extended loop
-                  Process_Closure (V, Callback);
-               end loop;
-            end if;
          end Process_Closure;
 
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