Execute dry-run RPC of constructor before deployment of a contract

[cmichi]

In https://github.com/paritytech/ink/issues/821 we found that debug messages which are printed in contract constructors do not appear on the console. Debug messages in functions of an instantiated contract appear though. This is because

Debugging is not enabled during on-chain execution. Only during RPC calls.

In order to support debug messages in constructors the UI should execute a RPC dry-run of the constructor before deployment of a contract.