Fixed variable rewriter

[PascalSenn]

Arguments that were mixed between variables and literals were not correctly rewritter

query vehicleMakes($id: Uuid!) {
  vehicleMakes(where: 
    {
      and: [
        {id: {eq: $id}}
        {isDisabled: {eq: false}} # was null
      ]
    })

[sonarcloud]

SonarCloud Quality Gate failed.

2 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

95.0% Coverage
0.0% Duplication