KAFKA-20524: Improve reset offset usability

[AndrewJSchofield]

This is part of the implementation of
https://cwiki.apache.org/confluence/display/KAFKA/KIP-1323%3A+Initialization+of+share+group+offsets+from+a+specific+offset+or+a+file.

Improves the readability of the usage messages for the command-line
tools for consumer groups, share groups and streams groups. For example,
the --export option used to say "Export offset information in CSV format" or "Export operation execution to a CSV file" which are a bit
misleading. The new text is "Generate offset reset information in CSV format for export to a file".

Also improves the output when bin/kafka-share-groups.sh is used to
reset the offsets for a group which is not a share group.

Before:

% bin/kafka-share-groups.sh --bootstrap-server localhost:9092
--reset-offsets --group CG1 --to-current --topic T1 --execute

Error: Executing share group command failed due to Failed altering group
offsets for the following partitions: [T1-0]
org.apache.kafka.common.errors.GroupIdNotFoundException: Failed altering
group offsets for the following partitions: [T1-0]

After:

% bin/kafka-share-groups.sh --bootstrap-server localhost:9092
--reset-offsets --group CG1 --to-current --topic T1 --execute

Error: Executing share group command failed due to Group CG1 is not a
share group. Failed altering group offsets for the following partitions:
[T1-0]
org.apache.kafka.common.errors.GroupIdNotFoundException: Group CG1 is
not a share group. Failed altering group offsets for the following
partitions: [T1-0]

The difference is that the error message "Group CG1 is not a share group" from the broker is included in the output.

Reviewers: Prakash Tanaji prakashtanaji@hotmail.com