refactor: Merge ClientConfig and BaseConfig interfaces

Closes #380 (closed) This merge request updates the TypeScript definitions in the GitLab web IDE codebase. It changes the names of several interfaces and types to make them more consistent and easier to understand. For example, ClientConfig is now called Config, and SerializableClientConfig is now called SerializableConfig. Additionally, some functions have been renamed to better reflect their purpose. These changes should make it easier for developers to use the GitLab web IDE and contribute to its development.