indexer p-chain example: block.Parse(b) codec-free — WHOLE NODE builds

Last P-chain codec consumer. go build ./... = EXIT 0. The platformvm codec
(pcodecs/txs.Codec/serialize tags) is fully dead; P-chain tx + block + state are
native ZAP struct-is-wire end to end. Remaining codec surface is X-chain +
proposervm + warp (Wave A), which still carry their own (intact) codecs.

Co-authored-by: Hanzo Dev <dev@hanzo.ai>

indexer/examples/p-chain/main.go

@@ -39,7 +39,7 @@ func main() {
 			platformvmBlockBytes = proposerVMBlock.Block()
 		}
 
-		platformvmBlock, err := platformvmblock.Parse(platformvmblock.Codec, platformvmBlockBytes)
+		platformvmBlock, err := platformvmblock.Parse(platformvmBlockBytes)
 		if err != nil {
 			log.Fatalf("failed to parse platformvm block: %s\n", err)
 		}