Add support for documents in separate projects, status filters and text work items

[micha91]

In this PR the following additional Features will be added:

• Documents can now be placed in a different project than the model sync work items
• You can define a list of document statuses which you want to allow document updates in
• It is now possible to define text work items in a document
  • A text work item can be defined in the document template by using the workitem tag: <workitem id="id">Some text</workitem>
  • The defined ID must be unique in the document
  • The ID will be stored in a custom field of the work item in polarion
  • By default the type of these workitems is text and the ID will be stored in custom field __C2P__id
  • You can overwrite this in the config by setting the text_work_item_type and text_work_item_id_field parameters in your config:

  - template_directory: jupyter-notebooks/document_templates
    sections:
      section1: test-icd.html.j2
      section2: test-icd.html.j2
    text_work_item_type: myType
    text_work_item_id_field: myId
    instances:
      - polarion_space: _default
        polarion_name: id1234
        section_params:
          section1:
            param_1: Test

[ewuerger]

Some things. After these I would give an approval.

[ewuerger]

LGTM.