Replace docserv-write-daps-param-file with Python code

[tomschr]

Situation

The scriptdocserv-write-daps-param-file is a separate script and is called inside Docserv. It has the following comment:

# FIXME: This should be removed as soon as possible again. This command is
# only a temporary workaround for the fact that Deliverable.execute
# does not allow redirecting into a file currently.

This design has some issues:

• It's inefficient as the internal state needs to be passed to the script (that's why it takes many options)
• Bash is slower than pure Python code

Proposed solution

• Integrate the functionality into Docserv code as Python.
• If really needed, provide a Python script that calls the internal code.