Improve hashed observable managment

[richard-julien]

Problem to Solve

Hashed observable generation key doesn't take into account all basic key of the stix standard.
We should use as a key MD5, SHA_1, SHA_256, SHA_512, SHA3_256, SHA3_512, SSDEEP
And accept custom hash only if one of the standard key exist instead of creating an UUID v4.
We also want to support key like mD5 applying basic case conversion.

Current Workaround

No

Proposed Solution

Modify the hashes key generation to respect the basic keys.
If no basic key found, throw an exception.