Add test constructor

[julienbrs]

Issue: related to #70

Description: Also added get_name to check the init value.

[julio4]

Would it be possible to test using the state directly and without the dispatcher and keep the ExampleConstructor contract as minimal as possible? Otherwise this looks good to me

I saw that you tried in the commits history, what was the problem by using unsafe_new_contract_state?

[julienbrs]

By using unsafe_new_contract_state, as far as I understand, we create a new instance of ExampleConstructor, but it's not deployed so construcor has never been called, leading to names not set.

[julienbrs]

Used set_contract_address that does the trick

[julio4]

LGTM! Thank you