soc: intel_adsp: tools: cavstool.py: Add debug_slot_offset_by_type()

Add debug_slot_offset_by_type() for getting debug window slot offset
by type identifier. How to find the correct slot and what types there
are is documented here:

soc/intel/intel_adsp/common/include/adsp_debug_window.h

In a normal situation a client program would try to find a specific
slot right after DSP boot. Because of that the we can not expect it to
be there immediately. Instead we need to try multiple times and give
firmware some time to update the debug slot descriptor table.

Signed-off-by: Jyri Sarha <jyri.sarha@linux.intel.com>