Create and read associations between HubSpot CRM objects using Associations API v4

Steps

1. To create an association, PUT to /crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/{toObjectType}/{toObjectId} with a body specifying associationCategory and associationTypeId
2. Retrieve available association type IDs by calling GET /crm/v4/associations/{fromObjectType}/{toObjectType}/labels
3. To read all associations for a record, GET /crm/v4/objects/{objectType}/{objectId}/associations/{toObjectType}
4. For bulk association creation, POST to /crm/v4/associations/{fromObjectType}/{toObjectType}/batch/create with an inputs array
5. To remove an association, DELETE to /crm/v4/objects/{fromObjectType}/{fromObjectId}/associations/{toObjectType}/{toObjectId}