Project: react-no-ts
Task (moderate):  1) Create context/BlogContext.jsx with React Context API to manage related context (blog list and selected blog) in App.jsx 2) When submit a new BlogForm, check title duplication. Constraint: The duplication check code should be written in BlogForm; 3) Add a span(.blog-list-len) near 'Hello Blog' in Header.jsx to show the length of blogs