+++ Refactor Class-Components to functional components +++

[BerkeAras]

• [ ] src/App.jsx:
• [ ] src/components/_App_CommentSection/index.jsx:
• [ ] src/components/_App_CreatePostForm/index.jsx:
• [ ] src/components/_App_PostsList/index.jsx:
• [ ] src/components/_User_FirstLogin/index.jsx:
• [x] src/components/Content/index.jsx:
• [x] src/components/Header/index.jsx:
• [x] src/components/HeaderDropdown/index.jsx:
• [x] src/components/SidebarLeft/index.jsx:
• [x] src/components/SidebarPopularItems/index.jsx:
• [x] src/components/SidebarRight/index.jsx:
• [x] src/views/App/index.jsx:
• [x] src/views/auth/LogOut/index.jsx:
• [ ] src/views/auth/PasswordReset/index.jsx:
• [x] src/views/auth/SignUp/index.jsx: