Language model and build compatible extensions API clarifications

[Ladicek]

• renamed BeanInfo.getName() to name() for consistency
• renamed ObserverInfo.observedType() to eventType() for clarity
• added SyntheticComponents.addObserver(Type) to allow registering
  synthetic observers of parameterized types
• changed WildcardType representation to always include an upper
  bound; the ? extends Object type is no longer represented as ?
  because the upper bound may be annotated
• improved specification of AnnotationTarget, especially around
  repeatable annotation types
• improved specification of ClassInfo and MethodInfo, especially
  around implicit declarations and abstract classes/methods

[Ladicek]

These changes are motivated by my TCK work. It should be the last batch of changes, at least to the language model, whose TCK should now be complete (jakartaee/cdi-tck#310). I'll continue working on the build compatible extensions tests, which may motivate some changes in the extension API, but hopefully minimal.

[Ladicek]

Actually I just realized that the commit message is wrong, the WildcardType does not always include an upper bound. It's that it always includes some bound -- either lower or upper. The unbounded wildcard is no longer represented as without bounds.