By default, esp-idf-size.ng displays all sections individually. This can
be confusing, especially if CONFIG_SOC_MEM_NON_CONTIGUOUS_SRAM is
enabled, resulting in sections like .dram0.data and .dram1.data being
abbreviated as two .data sections in the size report. To avoid confusion
for idf.py and cmake users, pass the --unify option to the underlying
esp_idf_size.ng by default.
Signed-off-by: Frantisek Hrbata <frantisek.hrbata@espressif.com>