Add mode to run kapt with JVM IR, use in tests

Currently JVM IR is not supported in kapt, so almost all tests are
failing, and thus are muted with IGNORE_BACKEND.

 #KT-49682

plugins/kapt3/kapt3-compiler/testData/converter/functions.kt

@@ -3,4 +3,4 @@ class FunctionsTest {
     fun f2() = fun (a: Int, b: Int) = a > b
     fun f3() = run {}
     fun f4() = run { 3 }
-}
+}