stream.sh position should support exact offset

Today we can change the position of a consumer to:

• the end of the stream
• after the appended date when using Kafka
• after a give watermark date when using computation Record
• to the beginning of the stream

but sometimes we want to use a known offset (like one reported in an error message).

Something like:

./bin/stream.sh position -k -l audit -g AuditLogWriter -p 0 --to-offset 15
... moving consumer group AuditLogWriter to position audit-00:+15

Also, stream.sh position -after-watermark needs to support the -codec option to be able to work with avro record.