Refine diagnostics for nullability migration warnings

#KT-24911 Fixed

compiler/testData/cli/jvm/jsr305/Annotated.java

@@ -5,4 +5,9 @@ public class Annotated {
 
     public void bar(@MyMigrationNonnull String x) {
     }
-}
+
+    @MyNullable
+    public String nullable() {
+        return null;
+    }
+}

compiler/testData/cli/jvm/jsr305/MyNullable.java

@@ -0,0 +1,15 @@
+import javax.annotation.*;
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import javax.annotation.meta.TypeQualifierNickname;
+import javax.annotation.meta.When;
+
+@Documented
+@TypeQualifierNickname
+@Nonnull(when = When.MAYBE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface MyNullable {
+
+}

compiler/testData/cli/jvm/jsr305DeprecatedWarn.out

@@ -1,5 +1,5 @@
 warning: argument -Xjsr305-annotations is deprecated. Please use -Xjsr305 instead
-compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: type mismatch: inferred type is Nothing? but String was expected
     a.foo(null)
           ^
 OK

compiler/testData/cli/jvm/jsr305Migration.kt

@@ -1,4 +1,5 @@
 fun test(annotated: Annotated) {
     annotated.foo(null)
     annotated.bar(null)
-}
+    annotated.nullable().length
+}

compiler/testData/cli/jvm/jsr305MigrationFqNameIgnore.out

@@ -1,4 +1,7 @@
-compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: type mismatch: inferred type is Nothing? but String was expected
     annotated.foo(null)
                   ^
+compiler/testData/cli/jvm/jsr305Migration.kt:4:5: warning: unsafe use of a nullable receiver of type String?
+    annotated.nullable().length
+    ^
 OK

compiler/testData/cli/jvm/jsr305MigrationIgnore.out

@@ -1,4 +1,7 @@
-compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: type mismatch: inferred type is Nothing? but String was expected
     annotated.foo(null)
                   ^
+compiler/testData/cli/jvm/jsr305Migration.kt:4:5: warning: unsafe use of a nullable receiver of type String?
+    annotated.nullable().length
+    ^
 OK

compiler/testData/cli/jvm/jsr305MigrationWarn.out

@@ -1,7 +1,10 @@
-compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Migration.kt:2:19: warning: type mismatch: inferred type is Nothing? but String was expected
     annotated.foo(null)
                   ^
-compiler/testData/cli/jvm/jsr305Migration.kt:3:19: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Migration.kt:3:19: warning: type mismatch: inferred type is Nothing? but String was expected
     annotated.bar(null)
                   ^
+compiler/testData/cli/jvm/jsr305Migration.kt:4:5: warning: unsafe use of a nullable receiver of type String?
+    annotated.nullable().length
+    ^
 OK

compiler/testData/cli/jvm/jsr305NoFlag.out

@@ -1,4 +1,4 @@
-compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: type mismatch: inferred type is Nothing? but String was expected
     a.foo(null)
           ^
 OK

compiler/testData/cli/jvm/jsr305Warn.out

@@ -1,4 +1,4 @@
-compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: type mismatch: inferred type is Nothing? but String was expected
     a.foo(null)
           ^
 OK