feat: add cortex-js

[namchuai]

Description

This PR refactors the Jan Server API into Cortex-JS, implemented using the Nest framework and structured according to the Clean Architecture.

src
├── domain                                       // Contains domain-related logic
│   ├── models                                   // Contains domain models
│   │   └── [context].interface.ts               // Interface files for domain models
│   └── repositories                             // Contains repository interfaces for interacting with data
├── infrastructure                               // Contains infrastructure-related logic
│   ├── controllers                              // Contains controllers for handling HTTP requests
│   ├── database                                 // Contains database-related logic (Framework-dependent)
│   ├── dtos                                     // Contains Data Transfer Objects (DTOs)
│   │   └── [context]                            // Specific context for DTOs (Framework-dependent)
│   │       └── *.dto.ts                         // DTO files for the specified context
│   └── entities                                 // Contains entity classes
│       └── [context].entity.ts                  // Entity files for the specified context (Framework-dependent)
└── usecases                                     // Contains use case logic
    └── [context]                                // Specific context for use cases
        └── [context].usecases.ts                // Use case files for the specified context

Introduces 3 levels of Providers and Extensions:

1. Internal Providers: Cortex-CPP, an internal reference that can access all use cases, repositories, and entities.
2. Core Extensions: Pre-installed extensions that require no additional actions.
3. External Extensions: The deployer can set an ENV to point to external extensions at runtime.

├── extensions                                  // Contains extensions-related logic
│   └── [core-extension-module]                 // Core extension module folder
└── infrastructure                              // Contains infrastructure-related logic
    └── providers                                // Contains provider-related logic
        └── cortex                               // Cortex provider folder
            └── cortex-provider-impl             // Cortex provider implementation folder

There are 3 commands supported:

// to pull a model
cortex pull {model_id}

// to start the cpp engine
cortex start

// to load a certain model
cortex load {model_json}

// Serve as API Server
cortex serve

[louis-jan]

#2784