376 remove backend

[ryankroon00]

Closes #376

What is it supposed to do
Removes the old backend and fixes a small issue with permissions when deleting a post

How can we test your branch
You can test the branch by testing all the functionalities.

Additional notes
You couldn't delete the posts due to some issues with permissions.

1. General checklist

• [x] a. Tested happy flow.
• [x] b. Tested unhappy flow.
• [x] c. No unexpected exceptions.
• [x] d. No code with high complexity. (Big O)
• [x] e. EOF newline.
• [x] f. No linter warnings or errors.

2. If relevant, front-end checklist

• [x] a. Responsive. (Desktop all the way to mobile 320px)
• [x] b. Using SCSS variables where relevant.
• [x] c. Relevant class names
• [x] d. No modified global SCSS properties, except if necessary and fully tested the impact.
• [x] e. Checked caniuse for more modern CSS properties.

3. If relevant, back-end checklist

• [x] a. No unhandled promise rejections.
• [x] b. Seeders still functional.
• [x] c. No primary-key violations.
• [x] d. Normalization, at least 3NF.
• [x] e. Used guards (middleware) where necessary and tested if route is guarded.

4. If relevant, test these browsers

• [x] a. Chrome
• [ ] b. Firefox
• [ ] c. Opera
• [ ] d. Edge
• [ ] e. Safari

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2. Select at least two reviewers.
3. Assign all reviewers allowed to merge the branch, including yourself.
4. If relevant to the sprint, put related issue in 'Awaiting Approval' column on project board.
5. Add to the corresponding milestone.

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