[Cosmos] Bulk Support

[TheovanKraay]

Describe the solution you'd like
Add bulk support for Python SDK in Cosmos DB

[tn-halfspace]

Yes please, it's a performance bottleneck in many cases for us...

[kushagraThapar]

Design choices:

1. Public API consideration: keep it simple.
2. Throughput control: to rate limit bulk operations, and not consume all RUs.
3. Adaptive batch size: based on workload pattern.