[CMAKE] Use CPack to build packages
This diff adds a new package build target, which creates one or more
output suitable for installation. For now limited to building a tar.gz
or zip archive of an installation directory, more coming later.
On all platforms:
Check the archive output is consistent with the items delivered in our
release binaries archives (requires D4229 for the libbitcoinconsensus
lib and include).
Reviewers: #bitcoin_abc, deadalnix, jasonbcox
Reviewed By: #bitcoin_abc, jasonbcox
Differential Revision: https://reviews.bitcoinabc.org/D4267