Break up hal debug files into multiple files.

Full list of hals installed on the device is preserved in
the main bugreport file. Now, for hals which implement
IBase::debug, their debug data is saved in one file
per hal. This is required so that hals can dump a
substantial amount of data (this change in particular
is motivated by wifi).

Fixes: 71597580
Test: bugreport on walleye shows data in the main list
  and in individual files.

Change-Id: I0bab88b2a98ec50f0c03eafd7e1e20a223e14bcc