Add `scala.language.{3.1, 3.1-migration}`

Fixes scala#13773

library/src/scala/runtime/stdLibPatches/language.scala

@@ -148,17 +148,33 @@ object language:
   @compileTimeOnly("`3.0` can only be used at compile time in import statements")
   object `3.0`
 
-/* This can be added when we go to 3.1
   /** Set source version to 3.1-migration.
     *
     * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
     */
+  @compileTimeOnly("`3.1-migration` can only be used at compile time in import statements")
   object `3.1-migration`
 
   /** Set source version to 3.1
     *
     * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
     */
+  @compileTimeOnly("`3.1` can only be used at compile time in import statements")
   object `3.1`
+
+/* This can be added when we go to 3.2
+  /** Set source version to 3.2-migration.
+    *
+    * @see [[https://scalacenter.github.io/scala-3-migration-guide/docs/scala-3-migration-mode]]
+    */
+  @compileTimeOnly("`3.2-migration` can only be used at compile time in import statements")
+  object `3.2-migration`
+
+  /** Set source version to 3.2
+    *
+    * @see [[https://scalacenter.github.io/scala-3-migration-guide/docs/scala-3-migration-mode]]
+    */
+  @compileTimeOnly("`3.2` can only be used at compile time in import statements")
+  object `3.2`
 */
 end language

tests/pos/source-import-3-0-migration.scala

@@ -0,0 +1 @@
+import language.`3.0-migration`

tests/pos/source-import-3-0.scala

@@ -0,0 +1 @@
+import language.`3.0`

tests/pos/source-import-3-1-migration.scala

@@ -0,0 +1 @@
+import language.`3.1-migration`

tests/pos/source-import-3-1.scala

@@ -0,0 +1 @@
+import language.`3.1`