Maintenance: Dockerfile and Setup for OpenUxAS

[dmgolembiowski]

The build process does a good job of assembling the pieces for building the container, however it can be greatly improved by either updating the README to account for the compile_commands.json requirement at docker build time. Additionally, the initial entrypoint does not seem to use the OpenUxAS source at the pinned SHA version. This could be achieved by either running hard-coded checkout commands, or by cloning at the required branch point into a temporary directory.