Migrate to github CI

.cirrus.yml

.github/scripts/build.sh

.github/scripts/common.sh

.github/scripts/prereq.sh

.github/scripts/test.sh

.github/workflows/caching.yml

.github/workflows/nix.yml

.github/workflows/release.yaml

.github/workflows/s3-cache.yaml

.github/workflows/test.yml

.gitlab-ci.yml

.gitlab/ci.sh

.gitlab/common.sh

.gitlab/tar.sh

.gitlab/test.sh

GNUmakefile

bindist/ghcs

bindist/ghcs-Darwin-arm

bindist/ghcs-Msys

haskell-language-server.cabal