Refactor SPG Contract into Multiple "Workflow" Contracts

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Description

The SPG contract is currently implemented as a single monolithic contract, which has now reached its size limit due to the addition of new functionalities. SPG needs to be restructured and the logic needs to be refactored into smaller contracts.

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The current plan is to break down the SPG into smaller "workflow" contracts. Some groundwork has already been completed in PR #43:

• Helper logic (interactions with core metadata modules, licensing modules, and the access controller) has been refactored into internal libraries for better reusability.
• Group IPA features have been moved into their own "workflow" contract (GroupingWorkflows).
• A BaseWorkflow contract has been introduced to consolidate shared logic across different workflow contracts, and both GroupingWorkflows and StoryProtocolGateway now inherit from BaseWorkflow.

Future Plans:

• The StoryProtocolGateway contract will be further divided into additional workflow contracts to reduce deployment size and improve gas efficiency (e.g., licensing workflows, IP registration workflows).
• Any new features added to the periphery (e.g., royalty, dispute management) will be implemented as separate workflow contracts.