`extra-executables` in cabal.project

[fgaz]

Describe the feature request
A new extra-executables field that specifies executables to be provided during development, such as linters and formatters. These should be solved independently from each other and from the main project.

The field should not contain executables that are needed to build the project. Those go in build-tool-depends, in the appropriate .cabal file

Additional context
Originally #7865 and #6952 (comment)

[mpickering]

I think this is a bit underspecified.

How is this field used? What commands would invoke these executables to be built, and how would they end up in the PATH?

[michaelpj]

I tend to agree. If we had a concept of a cabal-provided dev-shell, and the field was dev-tools or something, then it would make sense that when you go into the dev shell you get the dev tools on the path. But just saying they're "extra" is indeed rather unclear.

[andreabedini]

I would find this confusing since we already have extra-packages which are solved within the plan.

TBH I am -1 on adding dev environment management features to cabal.

If those executables have to solved independently; this would be equivalent to using cabal install to install them.