build(dev-container): use Node v16 & npm 7

We've upgraded to use npm 7 by default and because of that is easier
to default to Node 16 + npm 7 to avoid the flickering of the lock files
in version control.

Signed-off-by: Peter Somogyvari <peter.somogyvari@accenture.com>

.devcontainer/Dockerfile

@@ -45,10 +45,10 @@ CMD [ "sleep", "infinity" ]
 
 COPY post-create-commands.sh /home/vscode/bin/
 
-# Installing Node Version Manager (nvm) and Node v14 (current LTS)
+# Installing Node Version Manager (nvm) and Node v16
 USER vscode
 SHELL ["/bin/bash", "--login", "-i", "-c"]
 RUN curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.38.0/install.sh | bash
-RUN source /home/vscode/.bashrc && nvm install 14.17.0
+RUN source /home/vscode/.bashrc && nvm install 16.3.0
 SHELL ["/bin/bash", "--login", "-c"]
 USER root