refactor(excel-export): switch to explicit fflate/browser entry (#17122)

Author: damyanpetev

projects/igniteui-angular/grids/core/src/services/excel/excel-exporter.ts

@@ -1,4 +1,4 @@
-import { zip } from 'fflate';
+import { zip } from 'fflate/browser';
 
 import { EventEmitter, Injectable } from '@angular/core';
 import { ExcelElementsFactory } from './excel-elements-factory';

projects/igniteui-angular/grids/core/src/services/excel/excel-files.ts

@@ -2,7 +2,7 @@ import { IExcelFile } from './excel-interfaces';
 import { ExcelStrings } from './excel-strings';
 import { WorksheetData } from './worksheet-data';
 
-import { strToU8 } from 'fflate';
+import { strToU8 } from 'fflate/browser';
 import { ExportHeaderType, ExportRecordType, IExportRecord, IColumnList, IColumnInfo, GRID_ROOT_SUMMARY, GRID_PARENT, GRID_LEVEL_COL } from '../exporter-common/base-export-service';
 import { yieldingLoop } from '../exporter-common/yielding-loop';