Add tests for contact form

[MizukiTemma]

Short description

This PR adds tests for the features introduced by #3034

Proposed changes

Test following cases

• A contact is successfully created
• An existing contact is successfully updated
• A contact cannot be created if no POI is selected
• A contact cannot be created with all the fields empty
• A contact cannot be created without title and name if a primary contact already exists for the selected POI

Comment if you come up with other cases that need to be tested 😸

Side effects

• Reduced risk of bugs in future.

Resolved issues

Fixes: #3013

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