Provide a Redis compatible interface

[shuaimu]

• Port Redis interfaces support from https://github.com/Jiyang-Wu/MakoCon/tree/master/mako to Mako, with several basic interfaces support

[shenweihai1]

Experiments on https://github.com/Jiyang-Wu/MakoCon/tree/master/mako with multiple Redis interfaces supports.

We are planning to support several basic interfaces, such as string, list, hash, unsorted_set, and transactions. For transactions, the big difference between Redis and our transactional model is that, Redis returns a response for each operation inside this pipeline/txn. For example,

 r.execute_command("MULTI")
 r.execute_command("SET", "direct:key1", "value1")
 r.execute_command("SET", "direct:key2", "value2")
 r.execute_command("INCR", "direct:counter")
 r.execute_command("INCR", "direct:counter")
 results = r.execute_command("EXEC")
 print(f"Direct MULTI/EXEC results: {results}")   # results expected:   [b'OK', b'OK', b'1', b'2']