Switch to using a common `.project` file extension for projects?

[philderbeast]

Can we please change the project names to have a common .project file extension instead of a common cabal.project prefix?

$ tree -P 'cabal.project*' --prune -L 1
.
├── cabal.project
├── cabal.project.bootstrap
├── cabal.project.meta
├── cabal.project.release
├── cabal.project.validate
└── cabal.project.validate.libonly

1 directory, 6 files

I only use .project for full-blown projects. For imported project fragments I'll use .config.

If adopted, we'd have these project names;

$ tree -P '*.project' --prune -L 1
.
├── cabal.bootstrap.project
├── cabal.meta.project
├── cabal.project
├── cabal.release.project
├── cabal.validate-libonly.project
└── cabal.validate.project

1 directory, 6 files

[TeofilC]

Related issue: input-output-hk/haskell.nix#2144

It's helpful to have a common suffix to enable filtering for just cabal.project and imported files.
I imagine this would also be helpful for .gitignores and file highlighting.