Backend: results handling

# Feature
Using the new features of getting buildings between two buildings, and the rooms free within a time range for buildings, link them together to get the rooms free between two buildings (generate the result for the generate_free_room endpoint).

**Results Handling**
If no options then produce an error, otherwise if no rooms match the entire time
- return the longest time period possible (min 1 hr) then fill the rest with min 1 hour segments. If no 1 hr segments exist. ,then leave it empty
- 1 hour segments that can fill the range

It will return it in the **endpoints** structure design according to the documentation.

# Resources
- https://docs.devsoc.app/doc/backend-server-api-qbKAtkKG1a