Use cabal-install-3.4.0.0 on macOS in CI

Add release.py

A script essentially runs `v2-install cabal-install:exe:cabal`,
but does some simple setup, so the result is less luckily
to be influences by environment.

Also improve bootstrap to do out-of-tree builds.
- Use http, https tricky in some environments

Generate Paths module using zinza template

Bootstrap rewrite by bgamari

Ben Gamari authored 4 years ago and Oleg Grenrus committed 4 years ago

The plan: A JSON file (generated with bootstrap.py --extract-plan)
containing dependency and source information is built from plan.json.
This is then used to fetch and build the bootstrapping dependencies.
Since this is only to be used for bootstrapping on new architectures, we
advise the users to only use the resulting cabal-install executable to
build a proper cabal-install.

Bump random to 1.2

Make cabal-install-solver package

More warnings

Add cabal-version: 3.6 values

Add GHC-8.8.4 windows ci-job

Rename boot/ to templates/

The folder contains also `Lexer.x`, which isn't a template as such,
but it's not far from that, conceptually. `templates/` is better
name than `boot/`

Prune changelog.d, add new entries

Move cabal-install source to src/

Move Cabal sources into Cabal/src

Fix broken links in user's guide + few haddock fixes

Move doc/ to the top-level of the repository

Add active-repositories merge strategy: skip