fixes visoftsolutions#1

Description

This issue aims to enhance the functionality of VerkleTrie in two significant ways:

1. **Implementing `toDot` Method for String Representation:**
   
   * Develop a method `toDot` for `VerkleTrie` to create a human-readable string representation in [Dot format](https://en.wikipedia.org/wiki/DOT_%28graph_description_language%29). This feature will aid in debugging and visualizing the `VerkleTrie` structure.
   * The `toDot` method should include:
     
     * `BranchNodes` with `commitment` attribute.
     * `StemNodes` with `stem`, `leftCommitment`, and `rightCommitment` attributes.
     * `LeafNodes` with `suffix` and `value` attributes.
     * A `location` attribute for each node to uniquely name them.

2. **Implementing File Storing Mechanism for `toDot` Output:**
   
   * Extend the `toDot` functionality to include the capability of saving its output into a file. This addition will facilitate users in saving the `VerkleTrie` graphical representation for further analysis or sharing.
   * The file storing feature should:
     
     * Allow efficient and user-friendly saving of the Dot format output.
     * Handle errors related to write permissions or file system issues.
     * Optionally let users specify the file path and name for storing the output.

Expected Behavior

* `toDot` returns the tree representation in Dot format with specified attributes for different node types.

* Users can save the Dot format output of `VerkleTrie` into a file, enhancing the method's usability for debugging and analysis.