@ReadOnly annotation now could target ElementType.PARAMETER

it is done as a simplest way to avoid collision, because Kotlin have it's own `org.jetbrains.annotations.ReadOnly` which could be applied to parameters.

platform/util/src/org/jetbrains/annotations/ReadOnly.java

@@ -28,7 +28,7 @@ import java.lang.annotation.*;
  */
 @Documented
 @Retention(RetentionPolicy.CLASS)
-@Target({ElementType.METHOD, ElementType.FIELD, ElementType.LOCAL_VARIABLE})
+@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.LOCAL_VARIABLE})
 @ApiStatus.Experimental
 public @interface ReadOnly {
 }