feat(microservices): add commit-offsets function to clientkafka

[davidschuette]

This commit closes issue #9258.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: #9258

What is the new behavior?

ClientKafka provides access to commitOffsets function from kafkajs.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[davidschuette]

I will create a PR for the updated doc as soon as possible.

[coveralls]

Pull Request Test Coverage Report for Build 04e7878c-ea71-45a0-8a95-fe362ff0e61f

• 0 of 3 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.05%) to 94.11%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/microservices/client/client-kafka.ts	0	3	0.0%

Totals
Change from base Build 01266412-f77f-45f6-a650-ea1dafba9f72:	-0.05%
Covered Lines:	5720
Relevant Lines:	6078

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💛 - Coveralls

[kamilmysliwiec]

LGTM