Added admin club management (Add, edit, view a club & club datagrid)

[viviancan]

Refs #5170 & #5172

This PR adds the basic foundation of admin club management. Admin can

• Add a club (only the name is required), view a club, edit a club
• View all clubs on the Clubs datagrid

This PR also adds

• basic specs, clubs factory
• clubs model & basic validation for name and summary length
• null club

PS - specs are currently failing because the migration is in this PR