Disease index page and OMIM redirect

[egonw]

Addresses #924

Description

Adds a modern index page and redirection for OMIM identifiers:

Caveats

Only implements one of the suggested redirects.

Check any of the following which apply:

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
  • I have made corresponding changes to the documentation
• This change requires new dependencies (please list)

If you make changes to the Python code

• My code passes the tox check, I can receive warnings about tests, documentation or both

Testing

• Go to http://127.0.0.1:8100/disease/ and check if it looks like the above screenshot
• Click the redirect which should lead to https://scholia.toolforge.org/topic/Q191779

Checklist

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have not used code from external sources without attribution
• I have considered accessibility in my implementation
• There are no remaining debug statements (print, console.log, ...)

[fnielsen]

Documentation error