Provide isEnabled methods for CBORReadFeature and CBORWriteFeature

[wilkinsona]

While working on some Spring Boot configuration for CBORMapper, I've noticed that, unlike JsonMapper, CBORMapper does not have isEnabled methods for its format-specific features. I only really need them for testing that configuration has been applied correctly but they would certainly be useful for that. Symmetry with JsonMapper would perhaps be beneficial too.

[cowtowncoder]

Quick note: sounds reasonable. In the meantime I think you can use something like

cborMapper.tokenStreamFactory().isEnabled(CBORReadFeature.XXX)

NOTE: being API extension, needs to go in 3.1(.0)