Added dummy CMakeLists.txt files to the VS Code directories.

This is just to help the CI system to categorise merge requests that touch
files in these directories.

.devcontainer/CMakeLists.txt

+# This is a dummy CMake file meant only to help the CI system to categorise the files
+# that are in this directory. This file is not meant to have *any* meaningful CMake
+# configuration in it!

.vscode/CMakeLists.txt

+# This is a dummy CMake file meant only to help the CI system to categorise the files
+# that are in this directory. This file is not meant to have *any* meaningful CMake
+# configuration in it!

Projects/Athena/package_filters.txt

@@ -4,6 +4,8 @@
 
 # Technical package(s) that should not show up in packages.txt:
 - Build
+- .devcontainer
+- .vscode
 
 # Ignore the Projects directory:
 - Projects/.*