Add options for different themes for prismjs code snippets

[ezkemboi]

• Add an option that the user can choose themes when checking code.
• The default should be require('../node_modules/prismjs/themes/prism.css')
• You can add different themes in a object and user can choose from them e.g

      // Can add this function to main.js
      const chooseTheme = {
                default: require('../node_modules/prismjs/themes/prism.css'),
                okadia: require('../node_modules/prismjs/themes/prism-okaidia.css')
       }

• See an example screenshot of the firebase code snippet Link