Rdwv

We now use our new [universalasync](https://github.com/rdwvcc/universalasync) package to make this library running in both sync and async contexts

Therefore `get_event_loop` and `idle` functions were removed. They are accessible in the `universalasync` library.

Now `__del__` finalizer stores a client session per event loop which should be the most correct way to handle access from many different threads and loops

Major fixes for event loop handling
More exactly, our `__del__` finalizer should now work in all cases
No event loop mismatch issues are possible

Added new helper functions: `get_event_loop`, which gets current event loop via the following logic:

First it tries getting a running one, then main thread one, if it's not main thread or loop was stopped (i.e. not usable), it creates a new one
This function is useful as it will give a working event loop in 100% cases.

Another function added is `idle`. It can be run in main thread just to block the app and make event loop running (if your code is running asynchronously in other threads).

Also our tests now test all possible usage models of the SDK, and all of them are confirmed to work without issues (even mixing threads and so on).

Drop gzro support

Migrate test suite to testnet

Ensure no unclosed session warnings are shown

Fix handling of event loop when `asyncio.run` is unavailable

Properly use event loop
We now support using `asyncio.run` without crashes