[no-master] Remove @deprecatedNames that were introduced in 0.6.16.

It is not possible to cross-compile `@deprecatedName`s without
warnings between Scala 2.12- and 2.13+, because:

* In 2.12, they require symbol literals as arguments
* In 2.13, symbol literals are deprecated

Since they were deprecated more than two years ago, and are part of
an API that is not used much anyway (JS envs), I believe it is fair
to drop the source compatibility in this case.

Author: sjrd

js-envs/src/main/scala/org/scalajs/jsenv/ExternalJSEnv.scala

@@ -24,9 +24,7 @@ import scala.concurrent.{Future, Promise}
 import scala.util.Try
 
 abstract class ExternalJSEnv(
-    @deprecatedName('additionalArgs)
     final protected val args: Seq[String],
-    @deprecatedName('additionalEnv)
     final protected val env: Map[String, String])
     extends AsyncJSEnv {
 

js-envs/src/main/scala/org/scalajs/jsenv/nodejs/AbstractNodeJSEnv.scala

@@ -29,11 +29,8 @@ import scala.concurrent.TimeoutException
 import scala.concurrent.duration._
 
 abstract class AbstractNodeJSEnv(
-    @deprecatedName('nodejsPath)
     protected val executable: String,
-    @deprecatedName('addArgs)
     args: Seq[String],
-    @deprecatedName('addEnv)
     env: Map[String, String],
     val sourceMap: Boolean)
     extends ExternalJSEnv(args, env) with ComJSEnv {

js-envs/src/main/scala/org/scalajs/jsenv/nodejs/NodeJSEnv.scala

@@ -30,11 +30,8 @@ class NodeJSEnv(config: NodeJSEnv.Config)
 
   @deprecated("Use the overload with a NodeJSEnv.Config.", "0.6.18")
   def this(
-      @deprecatedName('nodejsPath)
       executable: String = "node",
-      @deprecatedName('addArgs)
       args: Seq[String] = Seq.empty,
-      @deprecatedName('addEnv)
       env: Map[String, String] = Map.empty) = {
     this(NodeJSEnv.Config().withExecutable(executable).withArgs(args.toList).withEnv(env))
   }