[SDK] Integrate shannon-sdk w/ Grove's portal gateway

[Olshansk]

Objective

Integrate shannon-sdk into portal-middleware

Origin Document

• The first independent iteration of the shannon-sdk is available here: [SDK] Initial implementation shannon-sdk#1
• It's first usage in poktroll is found here: [AppGateServer] Implement AppGateServer using ShannonSDK #554
• The first ieration of the documentation can be found here: https://dev.poktroll.com/develop/packages/sdk
• The first integration of shannon into portal-middleware can be found here: https://github.com/pokt-foundation/portal-middleware/pull/603

Goals

• Collect feedback on the new design of the Shannon SDK
• Put the foundation in place for future iterations towards Shannon

Deliverables

• Update https://github.com/pokt-foundation/portal-middleware/pull/603 using shannon-sdk
• Test an E2E Relay

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

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Creator: @Olshansk
Co-Owners: @red-0ne @adshmh