smithy4sUpdateLSPConfig: Plugin-inherited repos get rendered in duplicates (on file creation)

[kubukoz]

Reproduction:

1. sbt build

val subproj = project

val subproj2 = project.enablePlugins(Smithy4sCodegenPlugin)

val root = project
  .in(file("."))
  .aggregate(subproj, subproj2)

2. sbt plugin (in e.g. project/MyPlugin.scala)

package demo

import sbt.plugins.JvmPlugin

import _root_.sbt.Keys._
import _root_.sbt._

object MyPlugin extends AutoPlugin {
  override def trigger = allRequirements
  override def requires = JvmPlugin

  override def buildSettings: Seq[Def.Setting[_]] = Seq(
    resolvers ++= Resolver.sonatypeOssRepos("snapshots")
  )

}

3. Run smithy4sUpdateLSPConfig
4. Look at smithy-build.json:

{
    "version": "1.0",
    "imports": [
        "subproj2/src/main/smithy",
        "subproj2/target/scala-2.12/src_managed/main/smithy"
    ],
    "maven": {
        "dependencies": [
            "com.disneystreaming.alloy:alloy-core:0.3.4"
        ],
        "repositories": [
            {
                "url": "https://oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://s01.oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://s01.oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://s01.oss.sonatype.org/content/repositories/snapshots"
            }
        ]
    }
}

5. Run the command again
6. The json file now looks right:

{
    "version": "1.0",
    "imports": [
        "subproj2/src/main/smithy",
        "subproj2/target/scala-2.12/src_managed/main/smithy"
    ],
    "maven": {
        "dependencies": [
            "com.disneystreaming.alloy:alloy-core:0.3.4"
        ],
        "repositories": [
            {
                "url": "https://oss.sonatype.org/content/repositories/snapshots"
            },
            {
                "url": "https://s01.oss.sonatype.org/content/repositories/snapshots"
            }
        ]
    }
}

Ready-to-use reproduction: https://github.com/kubukoz/demos/tree/smithy4s-issue-lsp-config

[kubukoz]

Fixed in #1508 (0.18.17)