Reanimate Pig specific handling in the Avro parser

[a2l007]

Description

Apache Pig dependencies as well as related functionality were removed from the Avro parser in #7810
We internally use Pig extensively and the Pig specific transformation within the Avro parser extension is useful for us especially for parsing data bags. I would like to add the fromPigAvroStorage flag based processing back to the Avro Parser. In terms of tests, I can find a way to test this without adding the Pig dependency back.
I apologize for missing out on raising this concern on the original PR.

Any objections @gianm @Fokko ?

[gianm]

Hmm, I originally thought it made sense to drop Pig support since (a) it was blocking updating dependencies, and (b) it seems like Pig is no longer actively being maintained (the last release was 2.5 years ago).

But I guess I think that if Pig support can be re-introduced with good tests and without causing problems with getting stuck on old versions of dependencies, then that is fine by me. That was what @Fokko was trying to unblock originally in #7810.

@Fokko what do you think? (Also @ccaominh, any opinion? — I know you also did some dependency-management related work recently.)

[ccaominh]

As long as we can still use newer versions of dependencies I don't see any problems. (For example, avro needs to be on the latest 1.9.1 version as it addresses security vulnerabilities present in older versions.)

[a2l007]

Thanks for being supportive of the usecase. I've raised a PR for this.

[Fokko]

I'm fine with re-introducing pig support in a lightweight manner. It would be great if we can keep the pig dependency out of it since it hasn't been updated for a very long time.