[Additional] Re-assign a patient to another doctor

[QuangTran304]

Description: As an administrator, I want to re-assign a patient to another doctor when his/her doctor has an emergency to attend to so that the doctor focuses on the patient in the emergency

Linked to: #18

Acceptance criteria: Given: The user is logged in as an administrator and is on the patient list page. When: The user clicks on the dropdown under "Assigned Doctor". Then: The application shows a list of doctors that are available.

[MarwaKhalid]

Idea: (1) Add a dropdown to the list of patients table from which we can select and re-assign a doctor easily (similar to how we select and assign a milestone). (2) We can also have another dropdown to change the status of the patient, a patient can be positive first but then become negative.

Useful Links: https://codesandbox.io/s/iu8cd?file=/demo.js (we can try to do something like this for the positive/negative label) https://mui.com/components/selects/