Move JLine apis into LineReader

It is better that sbt not expose the implementation detail that
LineReader is implemented by JLine. Other terminal related apis should
be handled by sbt.internal.util.Terminal.

main-command/src/main/scala/sbt/BasicCommands.scala

@@ -9,7 +9,7 @@ package sbt
 
 import java.nio.file.Paths
 import sbt.util.Level
-import sbt.internal.util.{ AttributeKey, FullReader, JLine, Terminal }
+import sbt.internal.util.{ AttributeKey, FullReader, LineReader, Terminal }
 import sbt.internal.util.complete.{
   Completion,
   Completions,
@@ -34,7 +34,9 @@ import BasicKeys._
 import java.io.File
 
 import sbt.io.IO
+import sbt.util.Level
 
+import scala.Function.tupled
 import scala.collection.mutable.ListBuffer
 import scala.util.control.NonFatal
 
@@ -374,7 +376,7 @@ object BasicCommands {
     val history = (s get historyPath) getOrElse (new File(s.baseDir, ".history")).some
     val prompt = (s get shellPrompt) match { case Some(pf) => pf(s); case None => "> " }
     val reader =
-      new FullReader(history, s.combinedParser, JLine.HandleCONT, Terminal.wrappedSystemIn)
+      new FullReader(history, s.combinedParser, LineReader.HandleCONT, Terminal.wrappedSystemIn)
     val line = reader.readLine(prompt)
     line match {
       case Some(line) =>

main-command/src/main/scala/sbt/internal/ConsoleChannel.scala

@@ -29,7 +29,12 @@ private[sbt] final class ConsoleChannel(val name: String) extends CommandChannel
     private val history = s.get(historyPath).getOrElse(Some(new File(s.baseDir, ".history")))
     private val prompt = getPrompt(s)
     private val reader =
-      new FullReader(history, s.combinedParser, JLine.HandleCONT, Terminal.throwOnClosedSystemIn)
+      new FullReader(
+        history,
+        s.combinedParser,
+        LineReader.HandleCONT,
+        Terminal.throwOnClosedSystemIn
+      )
     setDaemon(true)
     start()
     override def run(): Unit =

main-command/src/main/scala/sbt/internal/client/NetworkClient.scala

@@ -15,7 +15,7 @@ import java.util.concurrent.atomic.{ AtomicBoolean, AtomicReference }
 
 import sbt.internal.langserver.{ LogMessageParams, MessageType, PublishDiagnosticsParams }
 import sbt.internal.protocol._
-import sbt.internal.util.{ ConsoleAppender, JLine }
+import sbt.internal.util.{ ConsoleAppender, LineReader }
 import sbt.io.IO
 import sbt.io.syntax._
 import sbt.protocol._
@@ -216,7 +216,7 @@ class NetworkClient(configuration: xsbti.AppConfiguration, arguments: List[Strin
   }
 
   def shell(): Unit = {
-    val reader = JLine.simple(None, JLine.HandleCONT, injectThreadSleep = true)
+    val reader = LineReader.simple(None, LineReader.HandleCONT, injectThreadSleep = true)
     while (running.get) {
       reader.readLine("> ", None) match {
         case Some("shutdown") =>