Add Transect property to Observation

As an API consumer, I want to be able to search observations by related transect id.

AC

• virtual property transect is added to observation
• getter for this property should return related transect (observation > sectionEvent > section > transect)
• search observations by transect id (ids) is possible, ie. search criteria can be specified in following way:

query {
  observations (
    transect_id_is: "123"
    transect_id_is_list: ["123", "223"]
  ) 
  {
    collection {
      id
    }
  }
}

• Tests

Review

• virtual property transect is added to observation
• getter for this property should return related transect (observation > sectionEvent > section > transect)
• search observations by transect id (ids) is possible, ie. search criteria can be specified in following way:
• Tests