dpc: fix comments spelling.
Debugger: Implement #9960.

- DebugReportGenerator now retrieves and dumps disassembly for the crashing
  function up to the crashing line.
HaikuDepot: Use PackageInfoRefs instead of PackageInfos

 Instead of storing PackageInfo objects directly in the
 PackageLists, store PackageInfoRefs instead. This makes a
 lot of operations much cheaper, and it also allows making
 changes to a PackageInfo (which now exists only once)
 and have those changes reflect everywhere. In particular,
 it will be easier to populate some information of the
 PackageInfo lazily, and to listen for changes on a
 PackageInfo object.
HaikuDepot: Add interface for PackageInfoListener.

 Also defines PackageInfoEvent.
Merge branch 'debugger_report_add_disassembly'