Add single key support

[citRaTTV]

Describe Pull request
Adds support for vehicles only having a single key as suggested by #241

Questions (please complete the following information):

• Have you personally loaded this code into an updated qbcore project and checked all it's functionality? yes
• Does your code fit the style guidelines? yes
• Does your PR fit the contribution guidelines? yes

[github-actions]

This PR has had 60 days of inactivity & will close within 7 days