move scala 2 test to sbt-test

Author: bishabosha

tests/pos/i16351/App.scala renamed to sbt-test/scala2-compat/i16351/app/App.scala

@@ -0,0 +1,13 @@
+val scala3Version = sys.props("plugin.scalaVersion")
+val scala2Version = sys.props("plugin.scala2Version")
+
+lazy val lib = project.in(file("lib"))
+  .settings(
+    scalaVersion := scala2Version
+  )
+
+lazy val app = project.in(file("app"))
+  .dependsOn(lib)
+  .settings(
+    scalaVersion := scala3Version
+  )

sbt-test/scala2-compat/i16351/build.sbt

@@ -0,0 +1 @@
+> app/compile