Making the migrate snippet script support already migrated json files and contributor array

Author: Mathys-Gasnier

snippets/css/layouts/grid-layout.md

@@ -14,5 +14,4 @@ Tags: css,layout,grid
 - `minmax(250px, 1fr)`: Defines a minimum column size of 250px and a maximum size of 1fr (fraction of available space).
 */
 }
-
 ```

utils/migrateSnippets.js

@@ -18,11 +18,11 @@ function formatSnippet(snippet) {
 Title: ${snippet.title}
 Description: ${snippet.description}
 Author: ${snippet.author}
-Tags: ${snippet.tags}
+Tags: ${snippet.tags}${('contributors' in snippet) && snippet.contributors.length > 0 ? `\nContributors: ${snippet.contributors}` : ''}
 ---
 
 \`\`\`
-${snippet.code.join('\n')}
+${Array.isArray(snippet.code) ? snippet.code.join('\n').trim() : snippet.code.trim()}
 \`\`\`
 `;
 }