Core: Relocate parquet to core

[danielcweeks]

This PR relocates the parquet implementation from the iceberg-parquet project to iceberg-core so that parquet can be used as part of metadata operations.

The project and artifacts are left so that dependencies still resolve and we can deprecate in a future release.

[ajantha-bhat]

Already we have a PR and issue tracker for the same
#8500

The project and artifacts are left so that dependencies still resolve and we can deprecate in a future release.

Since, Iceberg-parquet users will definitely use Iceberg-core, I assumed that we don't have to keep dummy modules and deprecate it in future. So, I removed them directly.

[nastra]

is there anything left in iceberg-parquet or can the gradle module be removed too?

[ajantha-bhat]

@nastra: He kept dummy module for compatibility. But I think it can be removed as mentioned in #11716 (comment)

My PR has end to end work, I can revive it.
#8500

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[ajantha-bhat]

Currently introducing internal writers for parquet: #11904

Once, it is merged, I will revive/rework the original #8500

[ajantha-bhat]

@danielcweeks: I have updated my old PR as per latest code. Please take a look.
#8500

Maybe this can go in for 1.8.0 too.

[ajantha-bhat]

Aah, I got the same Spark smoke test failure too. Let me debug this.

[danielcweeks]

Closing in favor of #12060