Add advanced examples for Cloudinary Go SDK

[arya2004]

Brief Summary of Changes

This PR extends the basic Cloudinary Go SDK usage examples by adding advanced functionalities with consistent code style and documentation comments. New examples demonstrate eager image transformations on upload, responsive srcset generation, video upload with transformations, single and bulk asset deletion, and paginated listing of assets.

What does this PR address?

• GitHub issue (Add reference - Enhance Example Project with Advanced Use Cases #112)
• Refactoring
• New feature
• Bug fix
• Adds more tests

Are tests included?

• Yes
• No

Reviewer, please note:

• This update strictly follows the coding format, commenting style, and structure of the original examples.
• The PR adds practical, real-world scenarios commonly needed in production apps using Cloudinary.
• No external dependencies were introduced; only SDK functionalities already available in cloudinary-go/v2 were used.
• No documentation changes needed because these examples extend existing code naturally.

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I ran the full test suite before pushing the changes and all the tests pass.

[const-cloudinary]

@arya2004 Thank you for PR, it does provide good real world examples.

Please fix the last example.

[arya2004]

added a simple condition to limit it to 4 assets by default

[const-cloudinary]

@arya2004, please fix two more small issues and we can merge it after that.

[arya2004]

@const-cloudinary I've updated the code with the requested changes. Please let me know if any further modifications are needed!

[const-cloudinary]

@arya2004 Thank you for contribution!