Reduce base dependencies from vcs and providers libraries

[mbarbin]

Vcs_base

In this meta-issue we document a multi-stages refactoring that occurred in the repository.

Targeted end result

The aim of this refactoring is to remove the base dependency of the Vcs library. To achieve this, we will offer two distinct libraries:

• Vcs - a kernel library that can be used with very little dependencies;
• Vcs_base - an extension of Vcs which will add some functionality related to working with Base.

Stages

Stage 1 - Introducing Vcs_base

• Completed: Oct. 2024 Initialize vcs-base refactor #31

In this stage, we create the library Vcs_base and setup the way in which this library extends Vcs. It exposes the same modules, plus extra functionality, such as:

• Base style hash signatures
• Comparable.S signatures for use with Base style containers
• Make some functions return sets instead of lists.

Stage 2 - Reducing ppx dependencies in Vcs

• Completed: Oct. 2024 Initialize vcs-base refactor #31

Only keep sexp related ppx that have no runtime dependency on base, such as sexplib0 only.

• Remove ppx_compare, ppx_here, ppx_let dependencies.

Stage 3 - Refactor non-raising APIs

• Completed: Oct. 2024 Vcs.Rresult (Vcs_base refactor) #33

• Rename Result => Rresult, introduce a new Result one.

Stage 4 - Trait implementation use Result

• Completed: Oct. 2024 Providers use Result (Vcs_base refactor) #34

Stage 5 - Move modules related to Or_error into Vcs_base.

• Completed: Oct. 2024 Move Or_error to Vcs_base (Vcs_base refactor) #35

Stage 6 - Remove base dependency from Vcs

• Completed: Oct. 2024 Remove base dependency (Vcs_base refactor) #36

Use vcs/src/import to make a local mini-stdlib with utils required to remove base dependency.

Do this for the other libraries:

• vcs
• vcs_command
• vcs_git_blocking
• vcs_git_eio
• vcs_git_provider