$queryRaw availability isn't derived from the DMMF

[dpetrick]

Blocks/depends on: prisma/prisma-engines#2087

If raw operations are not available for a connector, they are not rendered in the DMMF:

// ...
"mappings": {
    "modelOperations": [
      {
        "model": "Parent",
        // ...
      },
      {
        "model": "Child",
        // ...
      }
    ],
    "otherOperations": {
      "read": [],
      "write": []
    }
  }
// ...

However, the generated client still allows $queryRaw without complaining. This should be based on the available queries of the engine.

This is the object for a connector with raw query availability:

  "otherOperations": {
      "read": [],
      "write": [
        "executeRaw",
        "queryRaw"
      ]
    }