Add @Meta(resolver = …) attribute to customize Meta resolutions

[odrotbohm]

In the discussion of potential solutions for #4808, one idea was to add a resolver attribute to the @Meta annotation that could…

• either take a SpEL expression returning a fully populated Meta instance to be used for the query execution
• or refer to a named bean implementing a dedicated interface MetaResolver.resolve(RepositoryMethodContext) so that implementations get access to the full method

I guess both could be supported at the same time, but we might end up adding only one of the options.