fix: styling metadata array computing (#2060)

## Proposed change

Current computing mechanism is not working for styling metadata 

## Related issues

- 🐛 Fixes #2061

packages/@o3r/styling/builders/metadata-check/helpers/styling-metadata-comparison.helper.ts

@@ -12,7 +12,7 @@ export interface MigrationStylingData {
  * Returns an array of styling metadata from a metadata file.
  * @param content Content of a migration metadata file
  */
-const getCssVariablesArray = (content: CssMetadata): CssVariable[] => Object.values(content.variables);
+const getCssVariablesArray = (content: CssMetadata): CssVariable[] => Object.keys(content.variables).map((name) => ({...content.variables[name], name }));
 
 const getCssVariableName = (cssVariable: CssVariable) => cssVariable.name;