stellar-rpc-client: Use objects as parameters in every call #206

Job	Run time
Build (ubuntu-latest, x86_64-unknown-linux-gnu, amd64)	2m 23s
Integration tests (ubuntu-20.04, 1.22)	12m 59s
Build (ubuntu-latest, aarch64-unknown-linux-gnu, arm64)	3m 20s
Unit tests (ubuntu-20.04, 1.22)	6m 35s
Integration tests (ubuntu-22.04, 1.22)	13m 30s
Build (macos-latest, x86_64-apple-darwin, amd64)	7m 3s
Unit tests (ubuntu-22.04, 1.22)	2m 26s
Build (macos-latest, aarch64-apple-darwin, arm64)	3m 43s
Build (windows-latest, x86_64-pc-windows-gnu, amd64)	9m 3s
	1h 1m 2s

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