Initialize MemoryRecords builder with state from original request

[chris-giblin]

Currently during rewriting of partition data in encmod/src/main/java/io/strimzi/kafka/topicenc/EncryptionModule.java, a MemoryRecords builder is created mostly with default arguments. The builder however must be created with values matching the original request/response. This is a known limitation of the initial.

We do pass the baseOffset from the request but use default values for other fields such as compression type and timestamp type.

The derivation of the baseOffset must also be reviewed.