[CESQL] Added CONCAT_WS (#796)
[CESQL] Added CONCAT_WS (#796)

feat: CESQL: Add CONCAT_WS

* Concat should have a delimiter

Signed-off-by: Francesco Guardiani <56fdeb8ec48293e404ca3681b2b8738f930aab75@gmail.com>

* Added CONCAT_WS

Signed-off-by: Francesco Guardiani <56fdeb8ec48293e404ca3681b2b8738f930aab75@gmail.com>
cloudevents/spec