feat(devcontainer): adjust file permissions

Set the default umask to 022 within the devcontainer to ensure new files
are created with read permissions for all users.

Additionally, recursively add read permission to all existing files in
the devcontainer to ensure consistent access.

This improves collaboration and prevents permission issues when working
within the development container.

.devcontainer/post_create.sh

@@ -13,6 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# Set umask inside the container for new files.
+umask 022
+
+# Make sure all files have read everyone for existing files.
+chmod -R a+r ./*
+
 # Clean up minikube just in case to ensure a fresh cluster.
 make minikube-delete