[TECH] Supprimer la dépendance à ember-fetch dans Pix Admin.

admin/app/authenticators/oidc.js

@@ -1,7 +1,6 @@
 import { service } from '@ember/service';
 import { isEmpty } from '@ember/utils';
 import BaseAuthenticator from 'ember-simple-auth/authenticators/base';
-import fetch from 'fetch';
 import ENV from 'pix-admin/config/environment';
 import { decodeToken } from 'pix-admin/helpers/jwt';
 

admin/app/components/administration/access/oidc-providers-import.gjs

@@ -3,7 +3,6 @@ import { action } from '@ember/object';
 import { service } from '@ember/service';
 import Component from '@glimmer/component';
 import { t } from 'ember-intl';
-import fetch from 'fetch';
 import ENV from 'pix-admin/config/environment';
 
 import AdministrationBlockLayout from '../block-layout';

admin/app/routes/authentication/login-oidc.js

@@ -1,6 +1,5 @@
 import Route from '@ember/routing/route';
 import { service } from '@ember/service';
-import fetch from 'fetch';
 import get from 'lodash/get';
 import ENV from 'pix-admin/config/environment';
 import JSONApiError from 'pix-admin/errors/json-api-error';

admin/app/services/file-saver.js

@@ -1,5 +1,4 @@
 import Service from '@ember/service';
-import fetch from 'fetch';
 
 export default class FileSaverService extends Service {
   async save({