Add omim-directory console entrypoint

[jsstevenson]

e.g.

$ disease-normalizer omim-directory
/User/jss009/.local/share/wags-tails/omim
$ mv mimTitles.txt $(disease-normalizer omim-directory)/omim_20240625.tsv

Or write it to support all sources (which would make sense, actually...)

Also double check how error description looks if file is missing

[github-actions]

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