rpc: Use external soroban-simulation library for preflight computations #3209

Job	Run time
Build (ubuntu-latest, x86_64-unknown-linux-gnu, amd64)	2m 28s
Integration tests (ubuntu-20.04, 1.21, .CLI.)	21m 18s
Build (ubuntu-latest, aarch64-unknown-linux-gnu, arm64)	2m 52s
Integration tests (ubuntu-20.04, 1.21, ^Test(([^C])\|(C[^L])\|(CL[^I])).*$)	17m 34s
Unit tests (ubuntu-20.04, 1.21)	7m 36s
Build (macos-latest, x86_64-apple-darwin, amd64)	4m 32s
Integration tests (ubuntu-22.04, 1.21, .CLI.)	22m 49s
Unit tests (ubuntu-22.04, 1.21)	8m 10s
Build (macos-latest, aarch64-apple-darwin, arm64)	5m 54s
Integration tests (ubuntu-22.04, 1.21, ^Test(([^C])\|(C[^L])\|(CL[^I])).*$)	17m 23s
Build (windows-latest, x86_64-pc-windows-gnu, amd64)	7m 42s
	1h 58m 18s

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