Add core client traits for read-only and read-write IOTA operations

[itsyaasir]

Description of change

This PR is for adding the client interfaces as we discussed yesterday. This PR won't be merged in as the client traits will be transferred to products-core but I decided to do the leg work so it will be easy to transfer.

After the transfer, I will open an issue for the Identity clients to implements the traits as required.

All comments are welcome.

Links to any relevant issues

Be sure to reference any related issues by adding fixes issue #.

Type of change

Add an x to the boxes that are relevant to your changes.

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Fix

How the change has been tested

Describe the tests that you ran to verify your changes.
Make sure to provide instructions for the maintainer as well as any relevant configurations.

Change checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes