Style Linting & Automatic Prepush Lint and Test Check

Description

Current Behavior:

No style linter set up

Proposed Changes:

Added eslint, prettier, and husky (pre-push hook to check for lint and tests) for both frontend and backend
Added concurrently to start frontend and backend simultaneously

Issue Number(s): Closes #18, Closes #22

How Has This Been Tested?

npm run lint to run lint check and npm run lint -- --fix to apply automatic lint fixes
husky should run pre-push and run all lints & tests

Pull request type

Please check the type of change your PR introduces: - [ ] Bugfix - [ ] Feature - [x] Code style update (formatting, renaming) - [ ] Refactoring (no functional changes, no api changes) - [x] Build related changes - [ ] Documentation content changes - [ ] Other (please describe): ## Checklist Please check if your PR fulfills the following requirements: - [x] All new and existing tests passed - [x] Tests for the changes have been added - [x] Docs have been reviewed and added / updated if needed - [x] My code follows the code style of this project and lint has passed locally (we finally have lints now 😃)

MLH-Fellowship / CodeOfDuty