Pull in new JSON format

[reckart]

Describe the refactoring action

• Pull the code from https://github.com/apache/uima-uimaj-io-jsoncas into the main UIMAJ distribution as uimaj-io-json.
• Rename old JSON module to uimaj-io-json-legacy

Expected benefit

• Make JSON format directly accessible to UIMAJ users without having to draw in an artifact built from another repo (with a different version than UIMAJ).
• One release less to worry about.