Implement multiple packages, location variables, and standard price update

[sweep-ai]

Description

This PR implements the following changes:

• Created a new PackageController class to handle the creation, retrieval, update, and deletion of packages.
• Modified the PriceCalculator class to handle multiple packages, calculate the price based on volumetric weight or actual weight, and consider the location variables 'From' and 'To'.
• Updated the price_calculator_view file to allow users to add multiple packages and input the location variables.
• Modified the AdminController class to update the standard price in the PriceCalculator class.
• Added a getStandardPrice function to the PriceModel class to retrieve the standard price from the database.

Summary of Changes

• Created PackageController class with functions for package management.
• Modified PriceCalculator class to handle multiple packages and location variables.
• Updated price_calculator_view file to allow multiple packages and input location variables.
• Modified AdminController class to update standard price in PriceCalculator class.
• Added getStandardPrice function to PriceModel class.

Please review and merge these changes.

Fixes #1.

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