Allow providing custom cloud-init user-data template

[EconomicTouristsArmLate]

I want to customize for example the groups of the default user.

I tried to provide the template myself, but it doesn't get applied.
I'm not sure if its because of molecule (I'm new to it) or due to the way the template task chooses a template.

molecule
└── default
    ├── converge.yml
    ├── molecule.yml
    └── templates
        └── user-data.j2

[andreygubarev]

@EconomicTouristsArmLate thank you for your contributions, at the moment I don't have a recommended way on how to handle this kind of adjustments to default configuration. I check if it's possible to integrate in future releases.