Adding the registry read hive command

[RafBishopFox]

This PR adds the registry read hive command. It allows an operator to dump the contents of a registry hive to a binary file. The typical use case for this would be for dumping the SAM, SECURITY, and SYSTEM hives for use with a tool like secretsdump.

To dump the SAM hive for example, the command would look like this:

registry read hive -s SAM.save SAM

The command defaults to starting from HKLM. To dump SAM, SECURITY, and SYSTEM, Sliver has to be running with or be able to get the SeBackupPrivilege privilege and be running with High integrity. The command supports looting the resulting hive dump.

[lesnuages]

Small changes to make, otherwise looks good.

[RafBishopFox]

I had to remove support for running this command against a remote system because if you pass a remote key to RegSaveKeyW, it will save the dump file on the remote computer. That means we would have to build in functionality to retrieve and delete the file remotely. If we want to go down that route, I could work on adding that back in, but it would add a lot of complexity.

[rkervella]

Yeah no problem on focusing on the local host.