Merge `RecordEnricher` into `RecordTransformer`

[Jackie-Jiang]

RecordEnricher was introduced in #12243, which is very similar to RecordTransformer. It can cause confusion to maintain both of the abstractions because there is no clear boundary when to use which one.
We should merge RecordEnricher into RecordTransformer, and make the existing enrichers implement RecordTransformer interface. We might need to modify RecordTransformer a little bit to serve the purpose of RecordEnricher

[deepthi912]

Looking into it.

[aadilkhalifa]

@deepthi912 Are you working on this?

[deepthi912]

@aadilkhalifa Not currently working on it but you can work if you are willing to!