Support all the JFR event attribute types

[gunnarmorling]

• [x] boolean
• [x] char
• [x] byte
• [x] short
• [x] int
• [x] long
• [x] float
• [x] double
• [x] String
• [ ] Thread
• [x] Class
• [x] ClassLoader
• [x] StackTrace
• [ ] jdk.ReservedStackActivation::method: jdk.types.Method
• [ ] jdk.GCHeapSummary::heapSpace: jdk.types.VirtualSpace
• [ ] jdk.MetaspaceSummary::metaspace: jdk.types.MetaspaceSizes
• [ ] jdk.PSHeapSummary::oldObjectSpace: jdk.types.ObjectSpace
• [ ] jdk.G1EvacuationYoungStatistics::statistics: jdk.types.G1EvacuationStatistics
• [ ] jdk.PromotionFailed::promotionFailed: jdk.types.CopyFailed
• [ ] jdk.CompilerInlining::callee: jdk.types.CalleeMethod
• [ ] jdk.OldObjectSample::object: jdk.types.OldObject
• [ ] jdk.OldObjectSample::root: jdk.types.OldObjectGcRoot
• [ ] jdk.ModuleRequire::source: jdk.types.Module
• [ ] jdk.ModuleExport::exportedPackage: jdk.types.Package