HGMD Pro link-out missing in the vue interface

[stolpeo]

Is your feature request related to a problem? Please describe.
The HGMD Pro link-out can be enabled in the configuration and configured with a custom URL, but this is never used. Likely it was implemented in the old interface, but didn't make it to the new one, as mentioned in #739.

varfish-server/config/settings/base.py

Line 563 in 6a308f5

VARFISH_ENABLE_HGMD_PRO_LINKOUT = env.bool("VARFISH_ENABLE_HGMD_PRO_LINKOUT", default=False)

We need to either implement the link-out or discuss the usage. It was briefly mentioned in the meeting today, but I can't recall if we had any solution.

[xiamaz]

After discussion, this configuration option should be removed.