Add 'bloop output' command

Printing the output of the Bloop server, when available

modules/cli-options/src/main/scala/scala/cli/commands/bloop/BloopOutputOptions.scala

@@ -0,0 +1,21 @@
+package scala.cli.commands.bloop
+
+import caseapp._
+
+import scala.cli.commands.{LoggingOptions, SharedCompilationServerOptions, SharedDirectoriesOptions}
+
+// format: off
+final case class BloopOutputOptions(
+  @Recurse
+    logging: LoggingOptions = LoggingOptions(),
+  @Recurse
+    compilationServer: SharedCompilationServerOptions = SharedCompilationServerOptions(),
+  @Recurse
+    directories: SharedDirectoriesOptions = SharedDirectoriesOptions()
+)
+// format: on
+
+object BloopOutputOptions {
+  implicit lazy val parser: Parser[BloopOutputOptions] = Parser.derive
+  implicit lazy val help: Help[BloopOutputOptions]   = Help.derive
+}

modules/cli/src/main/scala/scala/cli/commands/bloop/BloopOutput.scala

@@ -0,0 +1,49 @@
+package scala.cli.commands.bloop
+
+import caseapp.core.RemainingArgs
+
+import scala.build.blooprifle.BloopRifleConfig
+import scala.cli.CurrentParams
+import scala.cli.commands.util.CommonOps._
+import scala.cli.commands.util.SharedCompilationServerOptionsUtil._
+import scala.cli.commands.{CoursierOptions, ScalaCommand}
+
+object BloopOutput extends ScalaCommand[BloopOutputOptions] {
+  override def hidden     = true
+  override def inSipScala = false
+  override def names: List[List[String]] = List(
+    List("bloop", "output")
+  )
+
+  def run(options: BloopOutputOptions, args: RemainingArgs): Unit = {
+    CurrentParams.verbosity = options.logging.verbosity
+    val logger = options.logging.logger
+    val bloopRifleConfig = options.compilationServer.bloopRifleConfig(
+      logger,
+      CoursierOptions().coursierCache(logger.coursierLogger("Downloading Bloop")), // unused here
+      options.logging.verbosity,
+      "unused-java", // unused here
+      options.directories.directories
+    )
+    val outputFile = bloopRifleConfig.address match {
+      case s: BloopRifleConfig.Address.DomainSocket =>
+        logger.debug(s"Bloop server directory: ${s.path}")
+        logger.debug(s"Bloop server output path: ${s.outputPath}")
+        os.Path(s.outputPath, os.pwd)
+      case tcp: BloopRifleConfig.Address.Tcp =>
+        if (options.logging.verbosity >= 0)
+          System.err.println(
+            s"Error: Bloop server is listening on TCP at ${tcp.render}, output not available."
+          )
+        sys.exit(1)
+    }
+    if (!os.isFile(outputFile)) {
+      if (options.logging.verbosity >= 0)
+        System.err.println(s"Error: $outputFile not found")
+      sys.exit(1)
+    }
+    val content = os.read.bytes(outputFile)
+    logger.debug(s"Read ${content.length} bytes from $outputFile")
+    System.out.write(content)
+  }
+}