Timestamp based consumption

[nanic]

Description

The fix provides with a new config option to consume from timestamp and also an optional end timestamp.

Fixes #121 (issue)

Type of change

Please delete options that are not relevant.

• [ ] New feature (non-breaking change which adds functionality)

Documentation

• [ ] a usage example was added to README.md

[d-rk]

Hey @nanic thank you for the PR. Can you please add tests for your change? Have a look here: https://github.com/deviceinsight/kafkactl/blob/main/.github/contributing.md#testing-your-changes

You can probably derive your tests from one of the other tests in https://github.com/deviceinsight/kafkactl/blob/main/cmd/consume/consume_test.go

[pierre-degrandmaison]

1 Question, 1 error:

1. Why "--exit" would be mandatory when using "--from-timestamp"? It should be allowed but optional.
2. When using "--end-timestamp", using "--exit" does not make any sense.

The consumer can start consuming from a particular timestamp and it is supposed to be used in tandem with --exit e.g.: kafkactl consume my-topic --from-timestamp --exit

There is an optional parameter to give end timestamp e.g.: kafkactl consume my-topic --from-timestamp --end-timestamp --exit

[d-rk]

closed in favor of the more complete PR https://github.com/deviceinsight/kafkactl/pull/147