Rename projects to have .project extension

[philderbeast]

Fixes #9925, renaming project files to have a .project extension.

Template Β: This PR does not modify cabal behaviour (documentation, tests, refactoring, etc.)

Include the following checklist in your PR:

• Patches conform to the coding conventions.
• Is this a PR that fixes CI? If so, it will need to be backported to older cabal release branches (ask maintainers for directions).

[TeofilC]

This looks good to me!

A minor point and this is liable to endless bikeshedding so feel free to ignore, but I have a mild preference for release.cabal.project over cabal.release.project. In my mind it's a cabal.project file so that should be the extension. Double barrel extensions like that are relatively common, eg, .tar.gz. And we can avoid accidentally syntax highlighting/ nix filtering some other sort of .project file

[philderbeast]

@TeofilC thanks for the good suggestion but for this pull request I don't want depart too much from what we have by scattering the projects. With cabal.*.project they're still adjacent in vscode where I can see hidden files that add to the clutter;

$ tree -a --prune -L 1
.
├── AUTHORS
├── cabal.bootstrap.project
├── cabal.meta.project
├── cabal.project
├── cabal.release.project
├── cabal.validate-libonly.project
├── cabal.validate.project
├── CONTRIBUTING.md
├── .dockerignore
├── fix-whitespace.yaml
├── fourmolu.yaml
├── generics-sop-lens.hs
├── ghc-packages
├── .gitattributes
├── .git-blame-ignore-revs
├── .gitignore
├── .gitlab-ci.yml
├── .hlint.yaml
├── id_rsa_cabal_website.aes256.enc
├── LICENSE
├── .mailmap
├── Makefile
├── README.md
├── .readthedocs.yml
├── release-checklist.md
├── stack.yaml
└── validate.sh

1 directory, 27 files

[philderbeast]

A minor point and this is liable to endless bikeshedding so feel free to ignore, but I have a mild preference for release.cabal.project over cabal.release.project. In my mind it's a cabal.project file so that should be the extension.

Unrelated to this pull request but your suggested change @TeofilC prompted me to review the names I used with Updo. There are currently two sets;

• Canonical Targets: stack.yaml, cabal.project, stack.upgrade.yaml and cabal.upgrade.project.
• GHC-Prefixed Targets but here it is not just a *.cabal.project but instead ghc-x.y.z.dhall2config.project, ghc-x.y.z.dhall2cabal.project and ghc-x.y.z.dhall2stack.yaml. I'm trying to squeeze a lot of metadata into those filenames.

[philderbeast]

Label merge+no rebase is necessary when the pull request is from an organisation.

[ulysses4ever]

CI-related backport

[ulysses4ever]

@mergify backport 3.12

[mergify]

backport 3.12

✅ Backports have been created

• #10040 Rename projects to have .project extension (backport #9958) has been created for branch 3.12 but encountered conflicts