feat: Admin dashboard cards

[timiajayi]

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Description

Implement an endpoint that fetches the following
Total revenue
total users
total product
lifetime_sales
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Related Issue (Link to Github issue)

684>
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Motivation and Context

create endpoints that delivery value for Total revenue, total users, total product, lifetime_sales, to the admin dahsboard
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How Has This Been Tested?

was tested with postman and unit test
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Screenshots (if appropriate - Postman, etc):

[Get] /api/v1/statistics

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Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
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Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[timiajayi]

Merge conflict fixed