Improve tx dump/offline sign #533

Job	Run time
build-binaries	8m 57s
build-wasm (wasm, build-wasm-scripts, wasm/tx_.wasm wasm/vp_.wasm wasm/checksums.json )	3m 56s
check-packages	4m 53s
changelog	0s
build-wasm (wasm-for-tests, build-wasm-tests-scripts, wasm_for_tests/*.wasm)	3m 7s
rust-docs	6m 6s
lints	5m 16s
test-unit	10m 41s
test-wasm	4m 25s
test-integration	13m 14s
check-benchmarks	0s
test-e2e	0s
	1h 0m 35s

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