Unit test (server endpoints)

[Emi-HE]

This includes:

• Jest, Supertest dependency set up
• Server's endpoint's test suite structure (Not actually implemented yet)
• Dummy user and kitchen object file

The test still needs to be adjusted once we resolve the imports/exports mismatches, This PR is to make it easier to reference the test for everyone.

Sorry for the late PR. I messed up the branch management and had to overhaul everything.