[BETA_JAVA28] Implement strict/safe construction rules for record classes

The following code should compile with source level 28, but not with source level 28 + --enable-preview:

```
import java.util.List;
record Node(String label, List edges) {

static void nullCheck(Object arg, Object owner) {
if (arg == null) {
String msg = "null arg for " + owner.toString();
throw new IllegalArgumentException(msg);
}
}

public Node {
nullCheck(label, this); // Error with --enable-preview
nullCheck(edges, this); // Error with --enable-preview
}

}
```

javac reports:

```
X.java:12: error: reference to this may only appear after an explicit constructor invocation
nullCheck(label, this); // Error with --enable-preview
^
X.java:13: error: reference to this may only appear after an explicit constructor invocation
nullCheck(edges, this); // Error with --enable-preview
^
2 errors
```

See the section `Other construction enhancements` in https://openjdk.org/jeps/401

As this is not related value classes, I am farming out this task as a separate ticket - I may get to this only later.

Start with the supplied Node record reproducer and compile it with source level 28 both with and without --enable-preview. Read the “Other construction enhancements” section of JEP 401 alongside javac’s current diagnostics. Done means the example has the specified compile behavior and related regression coverage is passing.

Written by the indexing model from the issue text.