tx & VP ctx and tests refactors #796

Job	Run time
rust-docs	7m 16s
build-binaries	10m 29s
lints	5m 48s
check-packages	5m 27s
build-wasm (wasm, build-wasm-scripts, wasm/tx_.wasm wasm/vp_.wasm wasm/checksums.json )	4m 53s
build-wasm (wasm-for-tests, build-wasm-tests-scripts, wasm_for_tests/*.wasm)	3m 55s
changelog	0s
test-integration	16m 22s
test-unit	10m 51s
test-wasm	8m 34s
check-benchmarks	0s
test-e2e	0s
upload-coverage	14s
	1h 13m 49s

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