feat(source): support ingesting protobuf map

[xxchan]

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What's changed and what's your intention?

fix #13387

#17743

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
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[xxchan]

• feat(source): support ingesting protobuf map #18512 👈
• refactor(source): move protobuf to codec crate, and refactor tests #18507
• main

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[chenzl25]

LGTM