Implements createrawtransaction RPC method #2174

Job	Run time
Check Cargo.lock is up to date	8m 28s
Check deny.toml bans	45s
Install zebrad from lockfile without cache on ubuntu-latest	8m 59s
Check deny.toml bans --features default-release-binaries	45s
Check deny.toml bans --all-features	45s
Test stable on ubuntu-latest	40m 13s
Check deny.toml sources	48s
Test beta on ubuntu-latest	40m 17s
Check for unused dependencies	14s
Check deny.toml sources --features default-release-binaries	46s
Test stable on macos-latest	49m 38s
Check deny.toml sources --all-features	1m 6s
Test stable on windows-latest	1h 2m 9s
Test beta on windows-latest	1h 0m 16s
Open or update issues for OS integration failures	0s
	4h 35m 9s

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