[WIP] Refactoring: make client package for client related annotations.

[mneverov]

What this PR does / why we need it:

This PR introduces client package for client-header- and client-body- related annotations. This is the first step to add client-body-timeout annotations.
Addresses refactoring part of #12177

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

None above: refactoring only.

Which issue/s this PR fixes

partially fixes #12177

How Has This Been Tested?

make test; lua-test; kind-e2e-test

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

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