Add support for custom protocol with coursier

[MasseGuillaume]

In coursier, you can handle custom protocols by defining a protocol handler:
https://get-coursier.io/docs/2.0.10/extra.html#extra-protocols
https://github.com/coursier/coursier/blob/ce251d0288bf029e4eeb8700e8990178559a005d/modules/tests/jvm/src/test/scala/coursier/cache/protocol/TestprotocolHandler.scala

I'm currently implementing support for Google Artifact Resitory:
coursier/coursier#1987 (comment)

When dealing with artifact with protocol artifactregistry I need to have a plugin available in the classpath. Since lmcoursier is in the sbt launcher classpath, it's not available by adding libraryDependencies += ... in project/plugins.sbt like you would do for an sbt plugin. Therefore, I propose a way to explicitly declare the artifacts you need to handle the protocol handling.

Users of custom protocol can now specify dependencies to their handler via this sbt setting:

csrProtocolHandlerDependencies += "org.example" % "google-artifact-repository-coursier" % "0.1.0"

Depends on coursier/sbt-coursier#327

[987Nabil]

Is there anything that speaks against this? I'd really like to have this 🙂

[sideeffffect]

What is blocking this? It would be of great help for us.

[laughedelic]

⬆️ 🙏

[eed3si9n]

I think this PR should be on top of 1.9.x branch, since develop branch is for sbt 2.x.

[rolang]

It seems to be possible to set it via csrConfiguration as well? Adding it like that worked for us:

csrConfiguration := csrConfiguration.value.withProtocolHandlerDependencies(
  Seq("org.example" % "google-artifact-repository-coursier" % "0.1.0")
)