make settings update a proper PATCH request

[anthony2261]

Issue #, if available:
#174
Description of changes:
Backend:

• use exclude_unset instead of exclude_default of the model_dump function when updating by uuid
• use exclude_unset instead of exclude_none when model dumping in update_user_info

Frontend:

• when patching user info, only include values that have changed

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.