add support for initMethod and destroyMethod attributes of @Bean

[martinlippert]

Add support for initMethod and destroyMethod attributes of the @Bean annotation with:

• auto-completion showing method proposals (only with signatures that would fit; void no-arg methods, including those that are inherited from supertypes)
• go to definition, allowing the user to jump to the referenced method declaration

[manueljordan]

I think it is very valuable.

About the first bullet point

only with signatures that would fit; void no-arg methods, including those that are inherited from supertypes

Just in case, currently through the initMethod and destroyMethod elements is possible define to refer private methods too. Even more:

• consider if should be referred a method defined in a .class of a third party located in a .jar file

It without matter the method's visibility