0.5.0-alpha: support Iroha post-2.0.0-rc.2.0 features

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Upstream changes:

• feat(merkle): implement inclusion proof generation and verification iroha#5467
  • Added MerkleProof<T> struct (no first-class support in @iroha/core/crypto yet)
• feat(transactions)!: integrate trigger executions into the transaction model iroha#5471
  • Significantly changes the shape of blocks
• refactor: standalone genesis commit from configuration iroha#5488
  • Mostly internal SDK changes for tests setup
• refactor!: lazy block stream; async-only client streams iroha#5500
  • Changes client.ws.blocks(), returning an AsyncGenerator<SignedBlock> (API is not finalized)
• feat!: specify height order for block queries iroha#5510
  • Methods client.find.blocks() and client.find.blockHeaders() now require a payload like { order: Order.Ascending }

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Superseded by #263 (it was a mistake to push into this repo directly, as it made iroha-next branch protected which I can't force-push).