unified syntax - upgrade refactor (multi-upgrade now possible) #791

Job	Run time
Contracts (nightly) / Clippy linter check	2m 1s
Contracts (nightly) / Wasm tests	16m 9s
Contracts (nightly) / Rust tests	3m 44s
Contracts (nightly) / Test Coverage	6m 46s
	28m 40s

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