Fix InaccessibleObjectException from JPMS in ThreadLocal cleaner

[OndroMih]

Before it logged a warning and stacktrace if java.lang not open on JDK 17+. But this situation is expected. If it happens, the thread local checker is just not executed, because it cannot get info about ThreadLocals from the JVM. Logs only a simple warning, with instructions how to open the package and enable the checker.

Also sets the context (appName) of the WebApp CL to the name of the app file as a fallback.

Before, the log message looked like this:

org.glassfish.web.loader.ReferenceCleaner checkThreadLocalsForLeaks
WARNING: Failed to check for ThreadLocal references for web application [unknown]
java.lang.reflect.InaccessibleObjectException: Unable to make field java.lang.ThreadLocal$ThreadLocalMap java.lang.Thread.threadLocals accessible: module java.base does not "opens java.lang" to unnamed module @1cc50131
	at java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:391)
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:367)
	at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:315)
	at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:183)
	at java.base/java.lang.reflect.Field.setAccessible(Field.java:177)
	at org.glassfish.web.loader.ReferenceCleaner.setAccessible(ReferenceCleaner.java:348)
	at org.glassfish.web.loader.ReferenceCleaner.checkThreadLocalsForLeaks(ReferenceCleaner.java:115)

[dmatej]

I was too late :-)