Cinema Page with Navbar adjustment

[sahedw]

Create Cinema page. Write fetch function to fetch movies which are currently in cinemas. Create MovieGrid Component for the new Cinema page. Fix required input field for the search and adapt the function. Add styling to poster with Styled Components. Adapt the Navbarto also have a cinema icon with highlighting etc. Refactor the fetch to a global leben with useContext. Fix the PushBack Button for Cinema page. Add small Component Test.