Kapt3: Fix a number of errors in ClassFileToSourceStubConverter:

1. Support strictfp modifier for methods.
2. Support Kotlin top-level methods and properties.
3. Fix visibility modifiers on enum methods.

plugins/kapt3/testData/converter/abstractMethods.kt

@@ -0,0 +1,9 @@
+abstract class Base {
+    protected abstract fun doJob(job: String, delay: Int)
+    protected abstract fun <T : CharSequence> doJobGeneric(job: T, delay: Int)
+}
+
+class Impl : Base() {
+    override fun doJob(job: String, delay: Int) {}
+    override fun <T : CharSequence> doJobGeneric(job: T, delay: Int) {}
+}