Performs migration of the key from PCSDK 4 to the current version of PCSDK.
The prerequisites to calling this method are the following:
Both PCSDK 4 and the current PCSDK are embedded into the same application
The key being migrated is active in PCSDK 4 (i.e., accessible via PCSDK 4 methods, not expired)
The given value of source and the certificate are obtained from PCSDK 4 method PCKey.exportRawWithCertificate(...).
The given value of password is the same as was used in PCSDK 4
Note that after the successful migration the key will present in both the current PCSDK and PCSDK 4.