API: save location 0,0

[koonchaya]

Context

When create/edit a site with location 0,0, api should return 0,0 instead of null so that the location shows on site information.

https://github.com/rfcx/arbimon/assets/87486094/fbe1e495-9051-45ad-b9e0-5a43ac39b94b

Expected results

• [ ] See the location of 0,0 after site created and tick in a checkbox "Exclude..." automatically
• [ ] See the location of 0,0 but location disable when click edit site and tick in a checkbox "Exclude..."
• [ ] Can untick the checkbox "Exclude..." and the 0,0 will be enable

[naluinui]

We'll keep it as it is (treating 0 as null) for now