Feat config aggr

[longfeiWan9]

This PR focuses on refactor the code base to better implement a configuration-driven approach for the aggregation service, buffer service, client and even deal service, etc.

• Codebase Refinements
  The update includes substantial code modifications to separate different components into a better go project structure. These changes aim to improve code readability, and maintainability, and easy to add more modular functions in the future. The new structure is:

  xchainClient/
  ├── cmd/
  │   └── xchain.go                # CLI entry point and command registration
  ├── config/
  │   └── config.go                # Configuration structs and loading functions
  │   └── config.json              # Describe all the configuration for xchainClient
  ├── services/
  │   ├── aggregator/
  │   │   ├── aggregator.go        # Aggregation service business logic (e.g., NewAggregator, run, sendDeal)
  │   ├── buffer/
  │   │   ├── bufferHttp.go            # Buffer service business logic (e.g., NewBufferHTTPService, startBufferService)
  │   └── client/                           # (Existing package) – contains client commands such as OfferFileAction
  │       └── client.go                  # Client repeated operations: testing offer data, new keystore, etc.
  │   └── deal/                            # (Existing package) – contains client commands such as OfferFileAction
  │       └── storageDeal.go      # Make storage deal on Filecoin via different approaches: directly with SP, through smart contracts. etc.
  ├── types/
  │   └── common.go                # Shared types used across packages (e.g., common API responses, timestamp mixins)
  ├── utils/
  │   └──  utils.go                 # Generic helper functions (e.g., context helpers, file/path utilities)
  ├── go.mod
  └── go.sum
  

• Configuration Integration for Aggregation Service
  When running the xchainClient, we can choose whether to run aggregation or not.

  • YES, xchainClient will run aggregation and sendDeal to SP
  • NO, xchainClient will directly make deals on Filecoin by calling ClientContract. (Need to be implemented)

This pull request represents a meaningful step forward in making the xchainClient more configurable and user-friendly, aligning with best practices for scalable application development.

closes #3

[longfeiWan9]

@snissn I am going to merge this. I have been testing xchainClien and it is working fine.