PR: Add Bulk WP menu at network level

[esudalaimadan]

Fix #671

@sudar Please look into multisite test issue i.e.,tests are erroring when run without WP_MULTISITE=1.

[esudalaimadan]

https://github.com/sudar/bulk-delete/blob/671-feature/add-mutisite-support-for-users-module/tests/wp-unit/include/Core/Users/Modules/DeleteUsersByUserMetaInMultisiteModuleTest.php is failing for single site though I am not loading this class for single sites.

Please let me know what am I missing.

[sudar]

Here is an overview of what got changed by this pull request:

Complexity increasing per file
==============================
- include/Core/Multisite/MultisiteAdminUIBuilder.php  3
- tests/wp-unit/include/Core/Users/Modules/DeleteUsersByUserMetaInMultisiteModuleTest.php  6
- include/Core/Users/UsersModule.php  2
- include/Core/Users/DeleteUsersInMultisitePage.php  1
- include/Core/Users/Modules/DeleteUsersByUserMetaInMultisiteModule.php  2
         

See the complete overview on Codacy