Revert workspace detection

[voodoos]

As discussed in the last dev meeting this PR restore the old root detection behavior: Dune will keep looking for an outermost dune-workspace file instead of stopping on the first one.

This is necessary to have dune ocaml-merlin provide configuration for nested vendored project with their own workspace file.

Fixes #5187

(partial revert of #4921)

[bobot]

I forgot during the meeting, but I wonder if @rgrinberg had a similar issue with RPC (find where the rpc socket, i.e. the data provider is) , and proposed a way.

[ghost]

I think what you are thinking of is discovering the list of Dune servers currently running. That won't be of much help here as merlin works even without a Dune server running. In particular, when users call dune builld repeatedly as one-off commands without ever starting it in watch mode.

[ghost]

There was a weird merge in #4913. I'm re-working the doc.

[ghost]

@voodoos I pushed a commit to main to delete some doc that was re-added by accident in #4923. Could you rebase you PR?

[voodoos]

@jeremiedimino done

I had to reword a lot so it might be worth it to read it again to check that the behaviour is clear.
I think it is important to explain the precedence of dune-workspace over dune-project as it has bitten me and other users.

[ghost]

Agreed. @christinerose could you have a look at the documentation changes?

[christinerose]

Suggested a few grammar things.
Looks great!

[ghost]

Looks good!