Change subscription helper to use full list and domain instead of host-list?

[sebb <se...@gmail.com>]

The subscription helper currently shows the available lists using the
shorthand host-list format, rather than list@host.apache.org, for
example

whimsical-dev

instead of

dev@whimsical.apache.org

The latter is less ambiguous and easier to classify.
At present falcon and ode are listed as foundation projects,
presumably because they have retired.

If the domain and listname were presented separately it would also
allow the list to be shorter.
i.e. select the domain first, then the possible list names would be
presented in a separate drop-down.

I think it would be easier to use, but maybe I am missing something obvious.

Unless anyone spots an obvious disadvantage upfront, I could create a
PoC and we can see.

S.