marine_test: implement service integration testing

[ValeryAntopol]

marine_test: implement service integration testing

[dzmitry-lahoda]

1

fn empty_string(module1: marine_test_env::module1::ModuleInterface {

is

fn empty_string(module1: marine_test_env::module1::ModuleInterface)

2

let start_data = marine_test_env::service1::modules::db_module::Entry {}; // access to an internal module structure

not sure, i do not need access to internals, to low level

3

v1 and v2 are good enough. in v3 it is not clear order for state updates. it is kind of optimization of running tests, so until there are to many of these no need.

[ValeryAntopol]

@dzmitry-lahoda thank you!

1. Fixed.
2. It allows using v2 instead of v1, so gives choice to the user, and does not cost much to implement.
3. It is not just an optimization. v3 also allows writing utility functions that use structs from marine_test_env, when other versions allow only utility macros. And it is not required to create global services, you can create new services for every test.