Allow use of enhanced docker image

[MichaelRossner]

Is your feature request related to a problem? Please describe.
For additional task often additional tools are required.
These tools can be installed in a docker image, derived from the original docToolchain docker image.
It should be possible to change the docker image used by the dtcw.

Describe the solution you'd like
Add an optional parameter to dtcw to pass the required docker image name.

Describe alternatives you've considered
none.

Additional context
none.

[MichaelRossner]

added MR #1326

[MichaelRossner]

Closed with merge of #1326