This ensures correct handling of attrnames with a dot in them and will
not throw errors about illegal attrnames.
Additionally this escapes any attributes containing dots in the JSON
output and adds another field called `attrPath` which contains the
attribute path as a list.
Example output:
```
{
"attr": "hello",
"attrPath": [
"hello"
],
"drvPath": "/nix/store/n204jib73z55cp9s0rmw1c5v5q528j7v-hello-2.12.drv",
"name": "hello-2.12",
"outputs": {
"out": "/nix/store/h59dfk7dwrn7d2csykh9z9xm2miqmrnz-hello-2.12"
},
"system": "x86_64-linux"
}
```
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