Add pipeline and transaction

[CahidArda]

Adding pipeline and transaction feature as described in #45.

Majority of the update is complete. Next steps:

• [x] Docstrings
• [x] Context manager usage (with redis.pipeline() as pipe: ...)
• [x] Benchmarking
• [ ] Auto pipelining for asyncio

[linear[bot]]

DX-882 Add transactions and pipeline support to Python SDK

[CahidArda]

to benchmark the pipeline, I tried sending 100 incrby commands back to back

Code

Pure redis: ```py t1 = time.time() iter_count = 100 for i in range(iter_count): redis.incrby("marine", 10) val = redis.get("marine") assert val == str(iter_count*10) t2 = time.time() print(t2-t1) ``` Pipeline: ```py import time t1 = time.time() iter_count = 100 with redis.multi() as pipeline: for i in range(iter_count): pipeline.incrby("marine", 10) val = redis.get("marine") assert val == str(iter_count*10) t2 = time.time() print(t2-t1) ```

Runtimes:	Normal	Pipeline	Transcation
5.28 s	0.31 s	0.34 s