Add asdf.

I broke down. I need multiple versions of Python and a bunch of
different things on occasion.

Dockerfile

@@ -266,6 +266,9 @@ RUN apt-get update && \
     wget https://raw.githubusercontent.com/docker/compose/1.29.2/contrib/completion/bash/docker-compose -qO /etc/bash_completion.d/docker-compose && \
     wget https://raw.githubusercontent.com/ansible-community/molecule/1.25.1/asset/bash_completion/molecule.bash-completion.sh -qO /etc/bash_completion.d/molecule && \
     wget https://github.com/mrolli/packer-bash-completion/raw/master/packer -qO /etc/bash_completion.d/packer && \
+    git clone https://github.com/asdf-vm/asdf.git /opt/asdf && \
+    ln --symbolic --target /etc/profile.d/ /opt/asdf/asdf.sh && \
+    ln --symbolic /opt/asdf/completions/asdf.bash /etc/bash_completion.d/asdf && \
     mkdir -p /usr/local/share/ca-certificates && \
     wget https://s3.amazonaws.com/rds-downloads/rds-combined-ca-bundle.pem  -qO - | \
         awk '/-----BEGIN[A-Z0-9 ]*CERTIFICATE-----/ {n++} n > 0 {print > ("/usr/local/share/ca-certificates/rds-" (1+n) ".crt")}' && \
@@ -284,5 +287,6 @@ COPY --chown=root:root bash_completion.d/* /etc/bash_completion.d/
 LABEL com.github.containers.toolbox="true" \
       com.github.debarshiray.toolbox="true"
 ENV PATH /usr/local/lib/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+ENV ASDF_DIR /opt/asdf
 VOLUME /run/sshd
 CMD ["/bin/bash"]