Enhance REST API to easier identify latest app version

The endpoint [GET /api/v1/platform/{platform-version}/apps.json](https://nextcloudappstore.readthedocs.io/en/latest/restapi.html#get-all-apps-and-releases) currently provides something like this for each app:

```
[
{
"id": "name",
"releases": [
{
"version": "1.0.0",
},
{
"version": "1.0.1",
}
]
}
]
```

This way it is difficult to identify the latest available release. In fact you have to iterate through all releases and do a version number comparison over the version value which is not simple and makes it impossible for apps that have no such logic like e.g. Ansible or other provisioning tools.

I'm asking to enhance the API such that we provide a latest release value and then also index the list by the version keys:

```
[
{
"id": "name",
"latest": "1.0.1",
"releases": {
"1.0.0": {
"version": "1.0.0",
},
"1.0.1": {
"version": "1.0.1",
}
}
}
]
```

Is that something that you are willing to support?