Fix: filter by category

[Odili1]

Description

Closes #412

Changes proposed

What were you told to do?

Add Category as an optional query parameter to filter products by an organization based on category
Add checks to verify that the category provided in the query is a valid category
Update the unit test for this handler to account for the changes made

What did you do?

Added Category as an optional query parameter to filter products by an organization based on category
Added checks to verify that the category provided in the query is a valid category
Updated the unit test for this handler to account for the changes made

Check List (Check all the applicable boxes)

🚨Please review the contribution guideline for this repository.

• My code follows the code style of this project.
• This PR does not contain plagiarized content.
• The title and description of the PR is clear and explains the approach.
• I am making a pull request against the dev branch (left side).
• My commit messages styles matches our requested structure.
• My code additions will fail neither code linting checks nor unit test.
• I am only making changes to files I was requested to.

Screenshots/Videos

• Successful Response without category query
  

• Successful Response with category query
  

• Error Response with Invalid category query
  

[Heba-WebDev]

Looks good.

[Heba-WebDev]

The title should be "Fix: filter by category"