add 'writeBinary(InputStream, int)' method in JsonGenerator

[cowtowncoder]

Current 'writeBinary()' method requires binary data to be passed as a byte array. This may not work well with larger payloads; so we should an alternative method where one can define source for binary data.
In addition to InputStream, it should be possible to indicate exact number of bytes to include; this because some formats (not JSON however!) require such information to be written before data, or used for initializing write. It should be possible to pass marker value -1 to indicate "not known": not all generators are required to support it, however.

[cowtowncoder]

Implemented (also for smile backend)