modules: lvgl: Add zephyr OSAL implementation

This patch adds the OSAL implementation of dynamic thread creation, mutex
and thread syncronization primitive (semaphore) enabling the use of the
parallel rendering architecture provided with LVGL 9.0. To use it, set
`CONFIG_LV_Z_USE_OSAL` and your preferred dynamic thread stack allocation
method (pool or heap).

Signed-off-by: Fabian Blatz <fabianblatz@gmail.com>