fix eslint warnigs for core project (#7506)

lib/core/utils/file-utils.ts

@@ -28,6 +28,7 @@ export class FileUtils {
         const files: FileInfo[] = [];
         return new Promise((resolve) => {
             const iterations = [];
+            // eslint-disable-next-line prefer-arrow/prefer-arrow-functions
             (function traverse() {
                 reader.readEntries((entries) => {
                     if (!entries.length) {
@@ -36,10 +37,10 @@ export class FileUtils {
                         iterations.push(Promise.all(entries.map((entry) => {
                             if (entry.isFile) {
                                 return new Promise<void>((resolveFile) => {
-                                    entry.file(function(file: File) {
+                                    entry.file((file: File) => {
                                         files.push({
-                                            entry: entry,
-                                            file: file,
+                                            entry,
+                                            file,
                                             relativeFolder: entry.fullPath.replace(/\/[^\/]*$/, '')
                                         });
                                         resolveFile();

lib/core/utils/moment-date-adapter.ts

@@ -194,6 +194,7 @@ export class MomentDateAdapter extends DateAdapter<Moment> {
         let isValidDateInstance = false;
 
         if (date) {
+            // eslint-disable-next-line no-underscore-dangle
             isValidDateInstance = date._isAMomentObject;
         }
 

lib/core/utils/object-utils.ts

@@ -19,6 +19,7 @@ export class ObjectUtils {
     /**
      * Gets a value from an object by composed key
      * ObjectUtils.getValue({ item: { nodeType: 'cm:folder' }}, 'item.nodeType') ==> 'cm:folder'
+     *
      * @param target
      * @param key
      */