Fix converting 28-bit DAB radio id to AIDL HAL id

Fixed converting deprecated 28-bit IDENTIFIER_TYPE_DAB_SID_EXT into
44-bit DAB_SID_EXT defined in broadcast radio HAL. Also fixed potential
null pointer exception when converting related contents of program info
in AIDL broadcast radio HAL service.

Bug: 300481687
Test: atest ConversionUtilsTest
Change-Id: I263a3a88c6b4259fa6b3b1d7489a63f4d079e6c0