Add supplier filters to contract BA view

• Add supplier info to the BA contract tree view
• Add filters by the three supplier categories

• Add a group by supplier option

Since if both mobile_contract_search_view and broadband_contract_search_view inherit from contract.contract_contract_search_view the filters needed in broadband where showed in both views (BA and mobile). Therefore, here we add a new (non inherited) search view for broadband with the new changes and the original code from the contract view + the corresponding translations brought from the original contract module.