Add ubuntu16 docker file to build scripts

Author: JamesWTruher

tools/docker/ubuntu16/Dockerfile

@@ -0,0 +1,12 @@
+FROM mcr.microsoft.com/powershell:ubuntu-16.04
+
+ENV __InContainer 1
+
+RUN apt update -qq && apt install -q -y wget git apt-transport-https
+RUN wget -q https://packages.microsoft.com/config/ubuntu/16.04/packages-microsoft-prod.deb && dpkg -i packages-microsoft-prod.deb
+
+RUN apt update -qq && \
+    cd / && \
+    git clone https://github.com/JamesWTruher/PSScriptAnalyzer
+
+RUN pwsh -c 'save-module -name platyps,pester -path $PSHOME/Modules'