CD-14: Setup the backend for Recipes page

[farnaf]

Deadline: Saturday (12/04/2021) before midnight (11:59PM)

In summary, firebase's database should be populated with at least 20 recipes that have ALL the required fields (title, image url, calories, description, ingredients, instructions) for a recipe.

The following are the tasks that MUST be worked on:

• [x] add 20 recipes (firebase documents) in public_recipe (firebase collection)
• [x] test and double-check that the function(s) in /public/backend/public_recipe.js work (frontend developers should be able to use these functions inside other JavaScript files, with no errors or odd behavior)

The following are the tasks that CAN (nice-to-have) be worked on:

• [ ] add 20 more recipes to the database

[Derrick2000]

Initially, we didn't design the category of "instruction", other than that it's all good