[1.10.x] Refs #16501, #26474 -- Added xregexp.js source file.

Backport of 054e74420b from master

.eslintignore

@@ -1,3 +1,4 @@
-**/{*.min,jquery}.js
+**/*.min.js
+**/vendor/**/*.js
 django/contrib/gis/templates/**/*.js
 node_modules/**.js

django/contrib/admin/options.py

@@ -575,7 +575,7 @@ class ModelAdmin(BaseModelAdmin):
             'actions%s.js' % extra,
             'urlify.js',
             'prepopulate%s.js' % extra,
-            'vendor/xregexp/xregexp.min.js',
+            'vendor/xregexp/xregexp%s.js' % extra,
         ]
         return forms.Media(js=['admin/js/%s' % url for url in js])