Refactor create_reader into static methods of DeviceReader

[bruno-f-cruz]

create_reader is currently the single entry point to create a DeviceReader. While easier to learn, it has some problems in that it tries to cramp a lot of functionality into a single method. Additionally, as we find different patterns we might want to use to create new readers, a single method will probably be very difficult to maintain. I propose deprecating it in favor of different methods in the DeviceReader class, what work as constructors of the type. Some that come to mind:

• .from_file (builds a DeviceReader from a .yml file)
• .from_url (builds a DeviceReader from a .yml file that must be downloaded from a URL)
• .from_str (builds a DeviceReader from a string that encodes a .yml file, this will probably also be the convergence point to the previous 2 methods)
• .from_model (builds a DeviceReader from a Model object)
• .from_dataset (or from_container (?), need a better name...) (builds a DeviceReader from a target .harp folder where a yml file is expected to be found and data is also expected to be found in a standard logging format).

Finally, with the exception of the last method, there is no way to infer what path _ReaderParams should use. The best we can probably do, is to assume the standard logging structure (yml in the same folder as the registers) and use it. The Reader will crash if the register reader method is called without arguments, but the reader will still work as intended if the path to the file is passed as an argument. In the future, we can think about ways to allow users to override this default behavior to support custom logging containers.