fix: patch root's .bashrc file to include completion

.devcontainer/cpp/Dockerfile

@@ -95,10 +95,12 @@ RUN --mount=type=cache,target=/root/.ccache,sharing=locked \
  && rm -rf /var/lib/apt/lists/*
 
 # Update all tool alternatives to the correct version
+# and patch root's bashrc to include bash-completion
 RUN update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++-13 20 \
  && update-alternatives --install /usr/bin/cc cc /usr/bin/gcc-13 20 \
  && update-alternatives --install /usr/bin/gcov gcov /usr/bin/gcov-13 10 \
  && update-alternatives --install /usr/bin/iwyu iwyu /usr/local/bin/include-what-you-use 10 \
  && update-alternatives --install /usr/bin/mull-runner mull-runner /usr/local/bin/mull-runner-${CLANG_VERSION} 10 \
  && update-alternatives --install /usr/lib/mull-ir-frontend mull-ir-frontend /usr/local/lib/mull-ir-frontend-${CLANG_VERSION} 10 \
- && update-alternatives --install /usr/bin/python python /usr/bin/python3 10
+ && update-alternatives --install /usr/bin/python python /usr/bin/python3 10 \
+ && cp /etc/skel/.bashrc /root/.bashrc

.devcontainer/rust/Dockerfile

@@ -39,7 +39,9 @@ RUN batstmp="$(mktemp -d /tmp/bats-core-${BATS_VERSION}.XXXX)" \
  && git -C /usr/local clone -b v2.1.0 https://github.com/bats-core/bats-assert.git
 
 # Update all tool alternatives to the correct version
-RUN update-alternatives --install /usr/bin/cc cc /usr/bin/gcc-13 20
+# and patch root's bashrc to include bash-completion
+RUN update-alternatives --install /usr/bin/cc cc /usr/bin/gcc-13 20 \
+ && cp /etc/skel/.bashrc /root/.bashrc
 
 # Install additional rust tools
 RUN wget -qO - "https://github.com/cargo-bins/cargo-binstall/releases/download/v${CARGO_BINSTALL_VERSION}/cargo-binstall-$(uname -m)-unknown-linux-gnu.tgz" | tar xz -C "/usr/bin" \