Pass one more argument to JsonSerializer.isEmpty()

[cowtowncoder]

Currently JsonSerializer.isEmpty() only takes a single argument, value to check.
But since some of configuration settings affect determination of emptiness (specifically, SerializationConfig.getSerializationInclusion()), it would make sense to pass SerializationConfig.
But it may be that some other per-call information will also be needed, so let's instead pass SerializerProvider, which gives full access to all available configuration.

Existing method needs to be deprecated, but supported for at least until 2.6 (and probably later); existing serializers should be upgrade in 2.5 to work with both methods.

[kellerassel007]

solved

[cowtowncoder]

@kellerassel007 Both issues are closed at this point: if there is a case that does not work with later versions (esp. 2.9.6), please file a new issue with reproduction. It may refer to this and/or 457 for context, but otherwise explain what is not working.