Introduce a compiler X flag to enable enhancing not null annotated type parameter's types to definitely not null types

compiler/testData/cli/jvm/extraHelp.out

@@ -27,6 +27,8 @@ where advanced options include:
   -Xemit-jvm-type-annotations Emit JVM type annotations in bytecode
   -Xjvm-enable-preview       Allow using features from Java language that are in preview phase.
                              Works as `--enable-preview` in Java. All class files are marked as preview-generated thus it won't be possible to use them in release environment
+  -Xenhance-type-parameter-types-to-def-not-null
+                             Enhance not null annotated type parameter's types to definitely not null types (@NotNull T => T & Any)
   -Xfriend-paths=<path>      Paths to output directories for friend modules (whose internals should be visible)
   -Xmultifile-parts-inherit  Compile multifile classes as a hierarchy of parts and facade
   -Xmodule-path=<path>       Paths where to find Java 9+ modules

compiler/testData/cli/jvm/kt49209.args

@@ -0,0 +1,6 @@
+-Xenhance-type-parameter-types-to-def-not-null
+$TESTDATA_DIR$/kt49209.kt
+$TESTDATA_DIR$/kt49209
+$FOREIGN_JAVA8_ANNOTATIONS_DIR$
+-d
+$TEMP_DIR$

compiler/testData/cli/jvm/kt49209.kt

@@ -0,0 +1,2 @@
+fun usingMethod(java : Java<String?>) : String = java.getFoo()
+fun usingProperty(java : Java<String?>) : String = java.foo

compiler/testData/cli/jvm/kt49209.out

@@ -0,0 +1 @@
+OK

compiler/testData/cli/jvm/kt49209/Java.java

@@ -0,0 +1,6 @@
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public interface Java<T extends @Nullable Object> {
+    @NonNull T getFoo();
+}