Symbolic links inside in/out directory not working

[tomuben]

Background

In #10 we add volume mount points for each directory given by the arguments.
However, if any of the directories contain symbolic links to paths which are not mounted, the container won't have access to those directories which might cause the respective docker run to fail.

For example assume the following scenario
$HOME
├── flavors
│   └── my_flavor
│   └── flavor_base
│   └── build_deps -> ../../../my_deps/
└── my_deps

running

./exaslct export --flavor-path=flavors/my_flavor --export-path ./out

will not work, as $HOME/my_deps will not be visible from within the container.

Acceptance Criteria

In starter_scripts/exaslct_within_docker_container.sh find all symbolic links of all mount point directories (given by command line arguments) and add to this list. As this might be very expansive, declare a new command line parameter --mount_symbolic_link_directories which enable/disables this functionality.

Alternative:

Add a command line parameter --mount-extra-directory which allows the user to specify additional directories which get mounted to the container. This would also solve problems with get_additional_build_directories_mapping configration in the flavors which in theory could point anywhere in the file system.