Flow fetch file refactoring

[Melisa-Zorraindo]

I made some reusable functions:

• checkForEmojis: check if a string is an emoji
• createFrontmatterTable: generates an html table with the frontmatter from the file if there is any
• displayDiff: displays the generated diff file
• displayPreview: displays the file with the most recent changes
• generateDiff: creates a new diff component
• styleCallouts: adds styling to the callouts

The frontmatter is now displayed as an HTML table.

The next step would be to enhance the fetch function to allow fetching any remote file. Currently, it has a hardcoded address - but I'll make a new PR for this feature.

[Fermain]

Thanks for this Melissa!