Show revert reason from nexus

[lukaw3d]

Replace "See why transaction was reverted in Oasis Explorer" with revert message from nexus.

But: initially nexus will only return "raw_message": "reverted: bLsWoQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAKAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAg=",
and only append readable message later "message": "reverted: ExceedsWalletLimit(10,8)",

https://testnet.nexus.oasis.io/v1/sapphire/transactions/a2029424e6b18a898c9ef15be545932d90dad75e0589f7256c337e84d7c830f1