PBS-39 feature: Add binlog encryption config and keyring support (part 7)

[percona-ysorokin]

https://perconadev.atlassian.net/browse/PBS-39

Added more diagnostics for keyring data, encryption configuration parameter and their combinations

• We now check that 'cipher' parameter in the keyring record is known to OpenSSL and is of 'ECB', 'CBC', 'CRT', or 'GCM' mode.
• We now check that the actual length of the 'data_hex' matches the one derived from the 'cipher' (i.g., 256 bit / 32 bytes / 64 hexadecimal characters for 'AES-256-CTR').
• We now check the uniqueness of the key IDs ('id' field) amongst keyring records.
• We also make sure that random file keys (of length that corresponds to the '<storage.encryption.cipher>' configuration parameter) can be encrypted with the active KEK ('<storage.encryption.kek_id>' configuration parameter). For instance, if active data cipher is 'AES-192-CRT' (key length 24 bytes), then the active KEK cannot be of 'ECB' or 'CBC' mode as these ciphers can only encrypt data of length that is a multiple of the block size (16 bytes).

'opensslpp::cipher_context' class extended with:

• 'get_mode()' (both static and non-static versions) that returns the cipher mode ('ECB', 'CBC', 'CRT', or 'GCM').
• 'is_cipher_name_known()' (static) - returns true if this cipher name is known to OpenSSL.
• 'is_mode_supported()' (static) - returns true if the mode is one of the 'ECB', 'CBC', 'CRT', or 'GCM'.
• 'is_cipher_name_supported()' (static) - returns true if this cipher name is known to OpenSSL and its mode is supported.

'cipher_context_test.cpp' (BOOST_TEST_MODULE CipherContextTests) unit test extended with the following test cases.

• 'CipherContextGetModeStatic' / 'CipherContextGetMode' that check for the behavior of the 'opensslpp::cipher_context::get_mode()' methods (both static and non-static).
• 'CipherContextCTRResume' that checks for "resume streaming" operation for 'XXX-NNN-CTR' ciphers - creating a new encryption context, updating it with some data, finalizing, creating a new context with offset, updating it with more data, and finalizing. The result of this operation should be identical to simple encryption of the concatenated data blocks from the first and the second updates.