Move org.openjdk.jmc.flightrecorder.configuration bundle from application to core

Summary: The org.openjdk.jmc.flightrecorder.configuration bundle contains many classes useful for working with jfr, and would be a great asset to have in core. It doesn't have any dependencies, so it shouldn't be too difficult to manage.

Additionally, there are a number of configuration-related classes that would be great to have in this bundle and could be incorporated at the time of migration. This includes:

org.openjdk.jmc.flightrecorder.controlpanel.ui.configuration.model.xml.*.java

• There are 12 classes that relate to JFC and XML grammar and validation, and these are not ui dependant like the classes in o.o.j.f.c.ui.configuration.model.gui so they can be moved safely

org.openjdk.jmc.flightrecorder.controlpanel.ui.model.VolatileStorageDelegate

• It would be nice to have VolatileStorageDelegate in the core bundle, as it's a read-only template. Additionally it would be nice to have EventConfiguration, but this has a dependency on rjmx.services.jfr which is not an easy movement of code.

In total, in addition to stock flightrecorder.configuration in core we'd also contain (13):

• org.openjdk.jmc.flightrecorder.configuration.model.VolatileStorageDelegate
• org.openjdk.jmc.flightrecorder.configuration.model.xml.IXMLValidator
• org.openjdk.jmc.flightrecorder.configuration.model.xml.JFCGrammar
• org.openjdk.jmc.flightrecorder.configuration.model.xml.JFCXMLValidator
• org.openjdk.jmc.flightrecorder.configuration.model.xml.PrettyPrinter
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLAttribute
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLAttributeInstance
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLModel
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLNode
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLNodeType
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLTag
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLTagInstance
• org.openjdk.jmc.flightrecorder.configuration.model.xml.XMLValidationResult

I have a branch where I have series of wip commits that accomplish this, and it seems to be working well at the moment: https://github.com/aptmac/jmc/tree/flightrecorder-configuration-to-core

The migration of flightrecorder.configuration is also required for rjmx classes to be moved to core, as tracked by https://bugs.openjdk.java.net/browse/JMC-7069