[Cosmos] add logic for parallelizing asynchronous queries

[simorenoh]

We are in general missing parallelization/ concurrent logic for executing document producers on the async side that could be leveraged to improve performance at the cost of more RU/s being consumed.

We would need a way to expose configuration settings to our users for them to decide on how parallelized a query should be depending on the performance/cost they are looking for.

• Exposing a new kwarg on the async query methods
• Syncing with other SDKs on default behaviors/ limits

We would need some solid benchmarking of before/after to get an idea of ratios, improvements, and any additional relevant info.

[kushagraThapar]

@tvaron3 - please take a look at this!