Add include defaults when describing topics

[rafiramadhana]

Description

Add --include-defaults flag when describing topics

kafkactl@sk-run-pod:~$ kafkactl describe topic topic-1 --output wide --include-defaults

I haven't done any integration test, but unit test run fine:

➜  kafkactl git:(177-describe-default-config) ✗ make test
fatal: No names found, cannot describe anything.
rm -f test.log
go test -v -short ./...
?   	github.com/deviceinsight/kafkactl	[no test files]
=== RUN   TestEnvironmentVariableLoading
--- PASS: TestEnvironmentVariableLoading (0.00s)

...

ok  	github.com/deviceinsight/kafkactl/util	(cached)

Fixes #177

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Documentation

• the change is mentioned in the ## [Unreleased] section of CHANGELOG.md
• the configuration yaml was changed and the example config in README.md was updated
• a usage example was added to README.md
• tests for the changes have been implemented (see: Testing your changes)

[mwarkentin]

Not much of a Go programmer, but with that in mind it seems good to me! :)

The tests seem to cover the new cases well.

[d-rk]

Hey @rafiramadhana
thank you for the PR 💯 . I reworked it a little so that there is only one parameter needed to control the "printConfigs".

I will try to build a release including this (and some other stuff) by the end of the week.

Cheers,
D.rk