Restructure and refactor classes related to SQL execution within the `EnvelopeGenerator.Infrastructure` namespace. Key changes include:
- Added `EnvelopeGenerator.Infrastructure.Executor` namespace.
- Moved and redefined `Query`, `QueryExtension`, `SQLExecutor`, `SQLExecutorBaseEntity`, and `SQLExecutorParams` classes to the new namespace.
- Maintained existing functionality while improving code organization and clarity.
This commit replaces the `AddEnvelopeGeneratorRepositories` method with `AddEnvelopeGeneratorInfrastructureServices`, allowing for more flexible configuration through `IConfiguration` and `Action<SQLExecutorParams>`. The `SQLExecutor` class now utilizes `SQLExecutorParams` for its connection string, enhancing configurability. A new `SQLExecutorParams` class has been introduced to encapsulate connection string management. Various service registration calls have been updated to integrate the new infrastructure services, improving modularity and ease of database connection management.
Updated the `AddSQLExecutor<T>` method in the `DIExtensions` class to register `ISQLExecutor<T>` as a scoped service instead of a singleton. This ensures that a new instance of `SQLExecutor<T>` is created for each request within the same scope, improving resource management and request isolation.
Removed `DIExtensions.cs` and integrated its content into `DependencyExtensions.cs`, enhancing the dependency injection setup with repository and SQL executor registrations. Added a new `CreateEnvelopeSQL` class implementing the `ISQL<Envelope>` interface, currently with a placeholder implementation.
