Merge branch 'feat/Workout' into 'develop'

front/src/api/UserAPI.js

front/src/api/workoutAPI.js

front/src/assets/explains.json

front/src/components/ExerciseBlock.jsx

front/src/components/Thumbnails.jsx

front/src/components/common/Header.jsx

front/src/components/index.css

front/src/components/user/SignIn.jsx

front/src/components/user/SignUp.jsx

front/src/components/workout/VideoDetails.jsx

front/src/components/workout/VideoLists.jsx

front/src/components/workout/VideoSelection.jsx

front/src/components/workout/secToTime.js

front/src/pages/MyPage.jsx

front/src/pages/Sign.jsx

front/src/pages/Workout.jsx

front/src/pages/index.css

front/src/pages/routine/progress.jsx