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"
}
```
This will respect `recurseForDerivations` when iterating over attrsets.
Example expression:
``` nix
{ system ? builtins.currentSystem }:
{
recurseForDerivations = true;
# This should build as it's in the top-level attrset
drvA = derivation {
inherit system;
name = "drvA";
builder = ":";
};
dontRecurse = {
# This shouldn't build as `recurseForDerivations = true;` is not set
# recurseForDerivations = true;
# This should not build
drvB = derivation {
inherit system;
name = "drvA";
builder = ":";
};
};
recurse = {
# This should build
recurseForDerivations = true;
# This should not build
drvC = derivation {
inherit system;
name = "drvC";
builder = ":";
};
};
}
```
The output of the evaluator should only include either the full
derivation (not yet implemented) or fields not directly accessible
from the drv such as meta.
Right now the output is a fairly arbitrary selection of fields.
