Adds signature help using Roslyn to provide contextual information
about method parameters and overloads as the user types.

This includes creating a tooltip that displays the method signature,
highlights the current parameter, and provides documentation.
Also enables navigation between method overloads using arrow keys.

Adds caching for completion item images to improve performance.

Automatically adds parentheses for method and extension completions.

Closes completion window only for truly invalid identifier characters.

Displays signature help when typing '(' or ','.

Separates the attached behavior logic into a dedicated extension class for better organization and clarity.
This enhances code maintainability and promotes reusability of the attached behavior functionality.

Disables debug mode in Roslyn completion and signature help behaviors.

This improves performance in production environments by removing unnecessary debugging overhead.

Removes an unnecessary line break in the GetSignatureHelpItemsAsync method declaration for improved code readability.