Once MVCC range tombstones are implemented (#70412) and supported in Export (#71398) we'll need to allow ingesting these SSTables via AddSSTable. Pebble should handle this just fine, so it's just a matter of handling it in the surrounding code (e.g. validation, timestamp rewrites, IngestAsWrites path, etc).

Jira issue: CRDB-13040

Epic CRDB-2624