Event Loop Management for asynchronous tests

Category: Development grant Tags: Client, QA Github handles: https://github.com/MementoRC Total HBOT requested: 10,000 HBOT Ethereum wallet: 0x8dA825941565a790BDf341B7099FA61296723756

Summary Proposing a few classes that help manage the Event Loop during tests. The idea is to use an isolated event loop (either with IsolatedAsyncio or new_event_loop) to run the tests. The event loop could be set at class level (not for IsolatedAsyncio) or at test-level> The key is the stop()/close() and reset of the existing event loop so that other tests do not fail (as is the case if 1 test uses IsolatedAsyncio)

The primary purpose is to allow to progressively adopt a more robust method for testing async methods, while not perturbing existing test library

PR: https://github.com/hummingbot/hummingbot/pull/6382