feat(core,common): Add @RawBody() decorator

[tolgap]

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: #13224

What is the new behavior?

Adds @RawBody() decorator

Does this PR introduce a breaking change?

• Yes
• No

Other information

[coveralls]

Pull Request Test Coverage Report for Build 4aa07adb-cf94-4972-b06e-a49d24bd6f18

Details

• -1 of 4 (75.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.009%) to 92.151%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
packages/common/decorators/http/route-params.decorator.ts	1	2	50.0%

Totals
Change from base Build 3bdf7d9b-d77b-45e6-ae7c-043c1979ed39:	-0.009%
Covered Lines:	6739
Relevant Lines:	7313

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💛 - Coveralls

[kamilmysliwiec]

lgtm