returning the formats in the way of:
```
"format": [
{
"format1" => 1,
"format2" => 1,
...
},
"defaultFormat"
]
```
is not a very good return format, since it abuses an array as a
tuple, and unnecessarily encodes a list of formats as an object.
Also, we can't describe it properly in JSONSchema in perl, nor our
perl->rust generator is able to handle that.
Instead, return it like this:
```
"formats": {
"default": "defaultFormat",
"supported": ["format1", "format2", ...]
}
```
which makes it much more sensible for an api return schema, and it's
possible to annotate it in the JSONSchema.
For compatibility reasons, keep the old property around, and add a
comment to remove with 10.0
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
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