Upgrades for whitelabel

[positonic]

Scope of work:
Scoping, assesement, testing etc [ 2 hours ]

Add the concept of an organisation link to registerWallet mutation. [ 2.5 hours ]
Add the concept and link to the organisation on addProject mutation. [2.5 hours]

Create organisationById mutation so that the client can get all organisation data (details, projects etc) from the organisation-resolver. [ 3 hours ]

Secure organisationById mutation, so that only a logged in user (connected to the organisation, and has sufficient permissions) is allowed to access this endpoint. [ 3 hours ]

**Total = 13 hours **

[positonic]

As per Giveth/giveth-planning#16

[willyogo]

Thank you James!

A 550 DAI bounty for this has been approved by the Giveth Foundation DAO 🎉 (view proposal)

Please let me know when this is ready for review!