refactor token transfer and add more tests #775

Job	Run time
build-binaries	11m 23s
check-packages	7m 26s
changelog	0s
build-wasm (wasm, build-wasm-scripts, wasm/tx_.wasm wasm/vp_.wasm wasm/checksums.json )	5m 27s
build-wasm (wasm-for-tests, build-wasm-tests-scripts, wasm_for_tests/*.wasm)	4m 50s
lints	7m 17s
rust-docs	8m 23s
test-integration	16m 50s
test-unit	10m 56s
check-benchmarks	0s
test-wasm	8m 12s
test-e2e	0s
upload-coverage	9s
	1h 20m 53s

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