dpapi.py QoL improvements

[Aptimex]

Three improvements:

• The unprotect command now auto-detects whether the supplied key is a "plaintext" key or a pre-hashed SHA1 key, rather than requiring the plaintext key. Most key-dumping tools output the SHA1 hash of relevant keys, so they can now be used directly.
• Added an -outfile flag to the unprotect command so decrypted files can be written directly to disk, which is often much more useful than a printed hexdump.
• All -key flags for all commands now handle hexstrings with and without a 0x prefix, rather than blindly and silently discarding the first two bytes of input.