[WIP] Site and Org associations

[dataclouder]

Add resources and data sources to handle site and org associations:

Data sources:

• [x] vcd_site to read site information
• [x] vcd_site_multi_site to get association data from current site
• [x] vcd_site_association to show information about an existing site association
• [x] vcd_org_multi_site to get association data from current org
• [x] vcd_org_association to show information about an existing org association

Resources:

• [x] vcd_site_association to create and remove site associations

• [x] vcd_org_association to create and remove org associations

• [x] Improve vcd_resource_list to show lists of vcd_site_association and vcd_org_association

To do:

• [x] Add import procedures
• [ ] Write comprehensive test
• [ ] Check data-source-not-found test
• [ ] Check org-user test
• [ ] Check binary test
• [ ] Write documentation for each resource/data source
• [ ] write a guide for site and org association operations
• [ ] Write examples for some association workflows