Implement report generation based on Word templates

[holtgrewe]

Is your feature request related to a problem? Please describe.
For generating persistent reports it would be useful to generate print-format reports based on Word templates.

Describe the solution you'd like
Allow users to upload Word .docx files as "mail merge" style templates (cf. https://pbpython.com/python-word-template.html). Make available the following information:

• case name
• index name
• HPO term list (ID + name/description)
• variants flagged as causative / candidate / ACMG 4/5
  • genome coordinates
  • gene / HGVS coordinates
  • extra annotations: CADD, SIFT, SpliceAI

Describe alternatives you've considered
N/A

Additional context
Related issue: #55

Useful components:

• docx-mailmerge for filling out .docx word mail merge templates
• gotenberg for rendering .docx to PDF
• pdf.js for rendering PDF in websites