Sushi examples should preserve the order of fields in the output

Nobody has claimed this yet.

Example resources can be difficult for users to inspect and understand since the fields are produced in a surprising order. Here's a minimal example of a simple patient -- notice the `active` and `gender` fields are moved to the bottom of the generated resource:

```
Instance: SimplePatient
InstanceOf: Patient
* active = true
* gender = #female
* address[+]
* use = #work
* address[+]
* use = #home
```

And the example output:

```
{
"resourceType": "Patient",
"id": "SimplePatient",
"address": [
{
"use": "work"
},
{
"use": "home"
}
],
"active": true,
"gender": "female"
}
```

Start by tracing how the compiler turns the shown FSH patient example into a JSON resource, then locate the serialization or resource-generation tests. Preserve the input field order in the generated output and add a regression case based on this example that verifies active and gender remain before the address fields.

Written by the indexing model from the issue text.