Refactor spec
Semantically name enterprises in spec
Determine producer options on order cycle screen through OpenFoodNetwork::Permissions class
Add EnterpriseRelationship scopes permitting and with_permission
Show permitted suppliers in order cycle add supplier select box
Show E2E related enterprise exchanges in OC
Change 'add products to OC' permission into the more general 'add enterprise to OC'
Add to OC permission allows adding distributors to order cycle
Permit edits to exchanges involving enterprises permitted via E2E relationships
Switch to correct grammatical ordering of child/parent enterprise on enterprise relationships page
Revert "Comment out ERPs which have confusing names, use old 'permits'"

This reverts commit a4be0ff55a2ef4cb7dd78412ca6a5018db6ab167.