Refactor Soroban decoding/encoding logic #7124

Job	Run time
Docs	1m 21s
Linux Arm	12m 41s
Container Image	11m 48s
Linux x86-64	27m 13s
Mac Arm	4m 55s
Mac Intel	12m 11s
Repolinter	1m 19s
Stdlib	2m 11s
Windows	8m 55s
Mac Universal Binary	0s
Soroban Integration test	0s
Solana Integration test	0s
Anchor Integration test	0s
Polkadot Integration test	0s
Polkadot Integration test with subxt	0s
Visual Code Extension	0s
Coverage report	0s
	1h 22m 34s

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