CSV Mapping fields aren't wrapped with quotes

**Describe the bug**
My export config has two lookup mappings defined which target string fields. When I extract as CSV (via the XRM ToolBox), these fields are not wrapped with quotes (`"..."`) like the other string fields. I'm not sure if this is because the lookup field is not defined in the Schema file?

The result of this is a broken CSV field if any mapping field value contains a comma (`,`).

**To Reproduce**
Within the Lookup Mappings, specify a lookup to a text field.
```json
{
"LookupMapping": {
"teamroles": {
"roleid": [
"name",
"businessunitid"
],
"teamid": [
"name",
"businessunitid"
]
}
}
}
```

**Expected behavior**
Mapped text values to also be wrapped with quotes.