New port: net-im/neochat

neochat is a KDE fork of net-im/spectral, using KDE technologies on
top of the Qt bits from spectral. It's not clear if spectral is still
being developed. If not, I'll deprecate the spectral port in a while.

One UI glitch is present, because of KDE Frameworks 5.75 -- the
requirement for 5.76 is patched out in the port, because 5.76
has not landed yet.