Define the interface for controlling how the Bigtable client retries RPC operations.
The C++ client for Bigtable needs to hide partial and temporary failures from the application. However, we need to give the users enough flexibility to control how many attempts are made to reissue operations, how often these attempts are executed, and how to signal that an error has occurred.
The application provides an instance of this class when the Table (or TableAdmin) object is created. This instance serves as a prototype to create new RPCRetryPolicy objects of the same (dynamic) type and with the same initial state.
Functions
clone() const
Return a new copy of this object.
Typically implemented as ```cpp
return std::unique_ptr
