Add Amazon DynamoDB Accelerator (DAX) support to the library

[BohdanKaminskyi]

Amazon DynamoDB Accelerator (DAX) is in-memory cache managed by Amazon that greatly improves performance (https://aws.amazon.com/dynamodb/dax/).
Amazon has dax-client for python (https://pypi.org/project/amazon-dax-client/) but it is synchronous.
Please, add ability to use DAX endpoints from the library

[ojii]

is there any implementation other than amazon dynamodb that can be used to test a client?

[BohdanKaminskyi]

is there any implementation other than amazon dynamodb that can be used to test a client?

Nothing I'm aware of. I could not find anything except https://pypi.org/project/amazon-dax-client/
Looks like internally it uses Session class supplied from boto

[ojii]

Since there's no reasonable way to automatically test this (we'd have to connect our CI to a real AWS account) and since I cannot find any description of the DAX protocol (other than the source code of the official clients), I'm not inclined to implement this and without a robust testing strategy, I would probably also not accept a PR for this either.