Compute SHA-256 in bundled_binary

[ikretz]

This PR updates the bundled_binary metadata rule so that it includes SHA256 hashes of the binary files it finds.

The output format is updated so that files are organized by unique hash. Each file listed on the same line has the same hash. These listed files are all distinct, even if they have the same name.

Sample output:

$ guarddog npm scan sample-package --version 1.1.0 --rules bundled_binary
Found 1 potentially malicious indicators in sample-package

bundled_binary: Binary file/s detected in package:
843b9ff549ab7a1d4a7d60cd224321058029350a88ccb53855969f3a8649a342: conpty.dll (exe), conpty.dll (exe), c.dll (exe)
c081c868cc3c6dc5ca6c950772cd04644c326a18e9727fb188683f214d517409: OpenConsole.exe (exe)
0269664950a8bc65f9d30cb1d64213b3fc50507a3c56c174516d3ae243cbc3e0: conpty.dll (exe)
1ac1552204d73b82873d253e66303fa3acfdbac2a0650f23b57c3450682afe56: OpenConsole.exe (exe)