Kafka client doesn't process unknown_server_error correctly and it may
lead to duplicates violating the idempotency. See the following issue
for more info: https://issues.apache.org/jira/browse/KAFKA-14034

request_timed_out just like unknown_server_error means that the true
outcome of the operation is unknown and unlike unknown_server_error it
doesn't cause the problem so switching to using it to avoid the problem

Update all partition::replicate dependees which don't perform offset
translation to bypass it via a direct raft reference

Updating consumer groups to use conditional replication to prevent a
situation when after a check a leadership jumps away, invalidates the
check, jumps back just in time for the post check replication.

check condition
  leadership goes to a new node
  the node replicates something which invalidates the conditions
  the leadership jumps back
the node successfully replicates assuming that the condition is true

Switched to a conditional replicate to fix the problem. When a group
manager detects a leadership change it replays the group's records to
reconstruct the groups state. We cache the current term in the state
and use it as a condition on replicate. In this case we know that if
the leadership bounce the replication won't pass.

We're going to mix raft and kafka offset in the same class, since
both the offsets uses the same type it's easy to make an error and
treat one as it was another. Introducing kafka offset to rely on the
type system to prevent such errors.

Shifting offset translation down the abstraction well to eventually
reach rm_stm

Preparing rm_stm to use kafka::offset based seq-offset cache. Right
now it uses raft offsets but there is a problem with it: once the
cache items become older that the head of the log (eviction) panda
becomes unable to use offset translation so we need to store already
translated offsets.

Since the cache is persisted as a part the snapshot so we need to
change the disk format and provide backward compatibility. The change
is splitted into two commits. Current commit introduces types to
represent old format seq_cache_entry_v1 and tx_snapshot_v1 and adds
compatibility machinary to convert old snapshot (tx_snapshot_v1) to new
snapshot (tx_snapshot).

The follow up commit updates the default types to use new format and
updates the mapping between old and default types.

switching to caching seq-kafka offsets cache to avoid out of
range errors on translating offsets beyond the eviction point

manually validated the tests by tweaking active_snapshot_version()
to ignore feature manager and to always use the newest version and
checked that in this case the tests fail