scripts/gdb/stackdepot: add stackdepot support

Add support for printing the backtrace of stackdepot handle.

This is the preparation patch for dumping page_owner,
slabtrace usage.

Link: https://lkml.kernel.org/r/20230808083020.22254-6-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Chinwen Chang <chinwen.chang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Qun-Wei Lin <qun-wei.lin@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>