Update Dockerfile (#5905)

- Install Clang
- Use the Ubuntu image to meet the CMake minimum

Author: gheber

.devcontainer/Dockerfile

@@ -1,5 +1,5 @@
-FROM mcr.microsoft.com/devcontainers/base:debian
+FROM mcr.microsoft.com/devcontainers/base:ubuntu
 
 RUN apt-get update && apt-get -y install --no-install-recommends \
-  build-essential cmake cmake-curses-gui default-jdk doxygen gfortran git graphviz \
+  build-essential clang cmake cmake-curses-gui default-jdk doxygen gfortran git graphviz \
   less libtool-bin libyajl-dev mpi-default-dev ninja-build pkg-config valgrind wget