add types-utils

[andelkocvjetkovic]

Hello, while working with this library, I had to create several type utilities to help me identify deltas. I believe these could also be helpful to others using this library.

This pull request adds several type guard functions to the packages/jsondiffpatch/src/types.ts file. These functions are designed to help identify specific types of Delta objects, improving type safety and code readability.

New type guard functions:

• isAddedDelta: Checks if a delta is of type AddedDelta.
• isModifiedDelta: Checks if a delta is of type ModifiedDelta.
• isDeletedDelta: Checks if a delta is of type DeletedDelta.
• isObjectDelta: Checks if a delta is of type ObjectDelta.
• isArrayDelta: Checks if a delta is of type ArrayDelta.
• isMovedDelta: Checks if a delta is of type MovedDelta.
• isTextDiffDelta: Checks if a delta is of type TextDiffDelta.