New formula for Eduardo Chappa's fork of UW Alpine, currently at version 2.11.

Per #26559, created new `alpine-chappa` formula for Eduardo Chappa's fork of UW Alpine, currently at version 2.11. Upstream site is here: http://patches.freeiz.com/alpine/. This seems to be the only place Alpine development is happening these days, as re-alpine is effectively dead. This formula conflicts with the `alpine` formula since they install the same binaries.