refactor: Add enum to check mime types results

api/src/common/interfaces/utilities.interface.ts

 export type Dictionary<T> = { [key: string]: T };
+
+export enum MIME_TYPES {
+  ERROR = 'text/plain+error',
+  WARNING = 'text/plain+warning',
+  USER_WARNING = 'text/plain+user_error',
+  HIGHCHARTS = 'application/vnd.highcharts+json',
+  JSON = 'application/json',
+  JSONBTREE = 'application/binary-tree+json',
+  PFA = 'application/pfa+json',
+  JSONDATA = 'application/vnd.dataresource+json',
+  HTML = 'text/html',
+  TEXT = 'text/plain',
+}

api/src/engine/connectors/exareme/converters.ts

+import { MIME_TYPES } from 'src/common/interfaces/utilities.interface';
 import { Category } from 'src/engine/models/category.model';
 import { Dataset } from 'src/engine/models/dataset.model';
 import { Algorithm } from 'src/engine/models/experiment/algorithm.model';
@@ -245,7 +246,7 @@ export const dataToRaw = (
   let data = result;
 
   if (algo === 'CART') {
-    data = { ...data, type: 'application/binary-tree+json' };
+    data = { ...data, type: MIME_TYPES.JSONBTREE };
   }
 
   return [