Export deprecated fields annotation keys

[JeromeJu]

Changes

This commit exports all the deprecated fields conversion annotation keys in v1beta1 to let pipeline pkg users be able to reference to them.

/kind misc
part of #7504

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[JeromeJu]

On second thought, do we actually need to export the annotation keys?

There shouldn't be any use case for a v1beta1 object to have annotations of deprecated fields with them. They can only appear in v1 objects' annotations so we shall probably use ConvertFrom first and check the respective fields?

[JeromeJu]

/hold