Fix thin client sbt process startup output

The boot server socket was not working correctly when the sbt server was
started by the thin client. This was because it is necessary for us to
create a ConsoleTerminal in order for System.out and System.err to be
properly forwarded to the clients connected over the boot server socket.
As a result, if you started a server instance of sbt with the thin
client, you wouldn't see any output util you connected to the server.
The fix is to just make sure that we create a console terminal if sbt is
run as a subprocess.

internal/util-logging/src/main/scala/sbt/internal/util/Terminal.scala

@@ -337,9 +337,10 @@ object Terminal {
    * @tparam T the result type of the thunk
    * @return the result of the thunk
    */
-  private[sbt] def withStreams[T](isServer: Boolean)(f: => T): T = {
+  private[sbt] def withStreams[T](isServer: Boolean, isSubProcess: Boolean)(f: => T): T = {
     // In ci environments, don't touch the io streams unless run with -Dsbt.io.virtual=true
-    if (hasConsole && !isDumbTerminal) consoleTerminalHolder.set(newConsoleTerminal())
+    if ((hasConsole && !isDumbTerminal) || isSubProcess)
+      consoleTerminalHolder.set(newConsoleTerminal())
     if (hasVirtualIO) {
       hasProgress.set(isServer && isAnsiSupported)
       activeTerminal.set(consoleTerminalHolder.get)

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

@@ -1160,7 +1160,7 @@ object NetworkClient {
       Runtime.getRuntime.addShutdownHook(hook)
       if (Util.isNonCygwinWindows) sbt.internal.util.JLine3.forceWindowsJansi()
       val parsed = parseArgs(restOfArgs)
-      System.exit(Terminal.withStreams(false) {
+      System.exit(Terminal.withStreams(isServer = false, isSubProcess = false) {
         val term = Terminal.console
         try client(base, parsed, term.inputStream, System.err, term, useJNI)
         catch { case _: AccessDeniedException => 1 } finally {

main/src/main/scala/sbt/Main.scala

@@ -79,13 +79,13 @@ private[sbt] object xMain {
         BspClient.run(dealiasBaseDirectory(configuration))
       } else {
         bootServerSocket.foreach(l => ITerminal.setBootStreams(l.inputStream, l.outputStream))
-        ITerminal.withStreams(true) {
+        val detachStdio = userCommands.exists(_ == BasicCommandStrings.DashDashDetachStdio)
+        ITerminal.withStreams(true, isSubProcess = detachStdio) {
           if (clientModByEnv || userCommands.exists(isClient)) {
             val args = userCommands.toList.filterNot(isClient)
             NetworkClient.run(dealiasBaseDirectory(configuration), args)
             Exit(0)
           } else {
-            val detachStdio = userCommands.exists(_ == BasicCommandStrings.DashDashDetachStdio)
             val state0 = StandardMain
               .initialState(
                 dealiasBaseDirectory(configuration),