Refactor Connection Management: Implement CanyonContext Singleton for Improved Configuration and Testability

[TheRustifyer]

Description:

The current implementation in core/connection/mod.rs relies on a lazy_static initialization alongside numerous functions, resulting in messy code that is hard to maintain and test. We need to streamline this by introducing a general singleton wrapper type (tentatively named Canyon or CanyonContext) that encapsulates the data and functionality currently scattered across the module.

This refactor will:

• Consolidate initialization logic and connection management into a single, well-structured type.
• Offer a fluent builder API for constructing a database connection via a datasource. This will empower end users to establish a connection even if a configuration file is absent.
• Address the current configuration file issue where the absence of the file triggers a panic!(). Instead, CanyonContext should gracefully return an error, with the potential addition of a new DatabaseType variant (e.g., NoDatabase) to support a Result-based error workflow.
• Improve testability by encapsulating state and exposing a clear, documented public API.

Tasks:

Design the CanyonContext Type:

• Define a new singleton wrapper type that holds:
  • Connection data
  • Configuration settings
• Ensure that the type is thread-safe and properly encapsulates all relevant state.

Migrate Lazy Initialization:

• Refactor the existing lazy_static setup into the new CanyonContext, ensuring a clean and maintainable initialization process.

Implement a Fluent Builder API:

Develop a builder pattern for CanyonContext that allows:

• Direct data input for runtime configuration.
• Optional loading of configuration from external sources (e.g., .env files or configuration files).
• Initialization of a database connection even if no configuration file is provided.

Improve Error Handling:

• Remove panic!() calls related to missing configuration files.
• Introduce proper error propagation (using Result) in the query executor branches.
• Add a new variant (e.g., NoDatabase) to the DatabaseType enum to support error workflows when no database configuration is available.

Refactor Existing Functions:

• Update functions within core/connection/mod.rs to utilize the new CanyonContext.
• Ensure that the new architecture integrates seamlessly with the rest of the codebase.

Testing:

Write comprehensive unit tests for:

• The initialization and lifecycle of CanyonContext.
• The fluent builder API, ensuring it handles various configuration scenarios.
• Correct error handling when configuration data is missing or invalid.

Expected Outcome:

A refactored connection module that:

• Encapsulates connection and configuration management in the CanyonContext singleton, leading to cleaner and more maintainable code.
• Provides a fluent and user-friendly API for constructing database connections.
• Handles missing configuration gracefully by returning errors, making the module more robust and testable.