Formalising our stance regarding binary distribution of cabal-install

I am growing increasingly convinced that the line between us, the upstream development team of Cabal & friends, and the distributors of the `cabal-install` tool is blurred.

Currently we have the following distribution channels:

* https://downloads.haskell.org/cabal: The "official" bindists produced by our gitlab release pipeline. It's not clear which downstream users benefit from it, as it is a subset of what ghcup distributes;
* GHCup: Through its own channel, distributes a wider variety of bindists, especially for platforms not maintained by the GitLab pipeline;
* Binary Distributions will build their own bindist because they will want to have a say on some lower-level linker & compiler flags, and they also get quite pissed off if they have to ship upstream binaries, see https://wiki.debian.org/Hadoop;
* Source Distributions don't care too much about our bindists.

Looking at these, I have the impression that we're not really using our time correctly in the Cabal team, since our bindists are neither covering all architectures that are requested, nor used by most of distribution channels.

I would like to ask our distributors if this impression is correct, and if there is something the Cabal team can focus on to ease their life, should we disengage from producing bindists ourselves.

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CC

@juhp for Fedora,
@arrowd for FreeBSD,
@blackgnezdo for OpenBSD,
@depressed-pho for NetBSD,
@branchvincent for Brew,
@hololeap and @solpeth for Gentoo
@rd235 for Debian,
@doko42 for Ubuntu,
@peti for OpenSUSE,
@maralorn for NixOS,
@hasufell for GHCup.

(Please indicate if someone else is better suited for your distribution.)

Start with the issue discussion and the listed distribution channels: the downloads.haskell.org/cabal bindists, GHCup, and downstream distributors. Review the distributor responses and linked Debian context; done means the Cabal team's role and a documented focus or decision about producing bindists are agreed.

Written by the indexing model from the issue text.