[java] Add config option to print 64-bit integers in JSON as unquoted ints if they can be losslessly converted into a 64-bit float

[mlmitch]

The title of this issue is taken from the following commit made in March 2023.
protocolbuffers/protobuf@330e10d

That commit added a configuration option to the C++ JSON printer for printing 64-bit integers in JSON as unquoted ints if they can be losslessly converted into a 64-bit float. This issue is a request for a similar configuration option to be added to the Java JSON printer.

Something like this has been in high demand from the community for a while, and the above commit feels like a great solution that also maintains JSON compatibility. Some previous issues around this topic:

• JsonFormat: why is Int64 being converted to a string ? protobuf#1823
• Why uint64, int64 Protobuf-Type be serialize as String JSON-Type in MessageToJsonString()? protobuf#2679
• protojson: Add MarshalOption to write int64 as a number and not as a string golang/protobuf#1414
• JsonFormat int64 converting protobuf#3194
• ProtoToJsonString : int64 is converted to string even when jstype=JSON_NUMBER protobuf#3423
• MessageToJson outputs the wrong type for uint64 and int64 in Python protobuf#2954
• The format is wrong when output int_64 to JSON.. protobuf#4103
• json_format.py is converting fixed64 to string protobuf#5942
• ... there are probably more

[mlmitch]

wrong repository - wow. my bad.