Add preview components

.gitignore

.storybook/preview.js

README.md

src/App.scss

src/_color-scheme.scss

src/components/Avatar.scss

src/components/Avatar.stories.tsx

src/components/Avatar.tsx

src/components/EventPreview.tsx

src/components/InviteTile.scss

src/components/InviteTile.stories.tsx

src/components/InviteTile.tsx

src/components/LinkButton.tsx

src/components/MatrixTile.tsx

src/components/RoomPreview.scss

src/components/RoomPreview.tsx

src/components/Tile.scss

src/components/UserPreview.scss

src/components/UserPreview.tsx

src/contexts/ClientContext.ts