net: lwm2m: Senml Json Base name dynamical update
net: lwm2m: Senml Json Base name dynamical update

SenML Json support dynamical basename for composite operation.
Changes simplify base name generation and compres message better.

Signed-off-by: Juha Heiskanen <da286ad296b3dcaa6fdad737a1ad7c3ff3e427db@nordicsemi.no>

galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr