Add discovery service to stable APIs

generated/googleapis/test/customsearch/v1_test.dart

 library googleapis.customsearch.v1.test;
 
 import "dart:core" as core;
 import "dart:collection" as collection;
 import "dart:async" as async;
 import "dart:convert" as convert;
 
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart' as http_testing;
 import 'package:unittest/unittest.dart' as unittest;
@@ skipping 786 matching lines @@
       res.list(arg_q, c2coff: arg_c2coff, cr: arg_cr, cref: arg_cref, cx: arg_cx, dateRestrict: arg_dateRestrict, exactTerms: arg_exactTerms, excludeTerms: arg_excludeTerms, fileType: arg_fileType, filter: arg_filter, gl: arg_gl, googlehost: arg_googlehost, highRange: arg_highRange, hl: arg_hl, hq: arg_hq, imgColorType: arg_imgColorType, imgDominantColor: arg_imgDominantColor, imgSize: arg_imgSize, imgType: arg_imgType, linkSite: arg_linkSite, lowRange: arg_lowRange, lr: arg_lr, num: arg_num, orTerms: arg_orTerms, relatedSite: arg_relatedSite, rights: arg_rights, safe: arg_safe, searchType: arg_searchType, siteSearch: arg_siteSearch, siteSearchFilter: arg_siteSearchFilter, sort: arg_sort, start: arg_start).then(unittest.expectAsync(((api.Search response) {
         checkSearch(response);
       })));
     });
 
   });
 
 
 }