Update module layout

[jazzz]

Problem

When importing the module in nim, the current layout leads to ambiguity and potential conflicts.

example:

import reliability
import message
import reliability_utils

This means:

• Developers must know where all types are located
  • e.g. ReliabilityManager is located in reliability_utils not reliability
• Ambiguous what files need to be imported
• message is generic and not tied to the sds module, easy to confuse with other modules

Solution

This PR adds a module folder sds to namespace imports, and adds a root level file to export required types.

result:

import sds

or

import sds/rolling_bloom_filter    # If importing specific files