Add parsing for 'Export' hives and boot key computation from class names

[MaxToffy]

Summary

This PR enables the parsing of registry hive files exported using regedit.exe or reg.exe export, along with the manual computation of the boot key. This functionality allows secretsdump.py to dump SAM and LSA secrets from these files.

registry-read.py / winregistry.py

The registry files exported via regedit are UTF-16 LE text files, which differ from the binary format produced by reg save. I implemented a parser in winregistry.py to handle these exported text files, and they can now be read using registry-read.py with the -format export option.

Boot key recovery

In secretsdump.py, boot key recovery typically relies on extracting class names from four specific registry keys within the LSA hive. However, the "export" hive format does not contain this metadata, making it impossible to retrieve the class names directly. You can recover the class names using two techniques outlined in the article “Dumping LSA secrets: a story about task decorrelation” written by @Dfte which inspired this PR.

Once you recover the class names, you can compute the bootKey using the following flags:

secretsdump.py

I introduced the -sam-export and -security-export flags to support dumping SAM and LSA secrets from these exported registry files:

[Dfte]

MAN THIS IS SO HOOOOOOOOOT !!! Thanks you for that PR!!