feat: modal basics, dropdown-menu, post/annoucement actions

package-lock.json

package.json

src/components/Button.jsx

src/components/annoucements/Announcement.jsx

src/components/annoucements/AnnouncementList.jsx

src/components/dropdown-menu/DropdownMenu.jsx

src/components/dropdown-menu/DropdownMenuItem.jsx

src/components/dropdown-menu/index.js

src/components/modals/Modal.jsx

src/components/modals/ModalConfirm.jsx

src/components/posts/Post.jsx

src/components/posts/PostList.jsx

src/containers/AddAnnouncementForm.jsx

src/containers/AddPostForm.jsx

src/containers/AnnoucementsContainer.jsx

src/containers/PostsContainer.jsx

src/index.js

src/pages/Home.jsx