Use of deprecated DES-CBC cipher

[stv0g]

The Encrypt() API defaults to the deprecated DES-CBC cipher, which can only be configured via the global variable ContentEncryptionAlgorithm.

The global variable should be elimnated and the alg be passed as an argument to the function.

This change requires a v2 of the package as it breaks the API.

See:

• [Bug]: Legacy DES-CBC cipher is used for encryption of PKCS#7 envelopes scep#16
• DES default micromdm/scep#218