Add Pagination Functionality, Organize Code, and Update Invoice Schema

[luis-serrano-l]

Changes Made:

1. Pagination Functionality:

   • Created live/show.ex and Added a pagination function component to handle pagination across the application.

2. Code organisation and readability:

   • Moved the invoice_navigation component from core_components.ex to live/show.ex for improved organization.
   • Moved short *.html.heex files into the render function for better code structure.

3. Invoice schema update:

   • Added a full_changeset changeset in the invoice schema to handle items.

Context:

• The pagination functionality enhances code reusability and simplifies future development.
• Improvements to code organization and readability streamline the codebase and improve maintainability.
• The update to the invoice schema enhances the handling of items within invoices.

Additional Information:

• Specs have been added to ensure code quality and correctness.
• Credo and Dialyzer checks have been passed, ensuring overall code quality.