chore: Improve VM property checking

[sdelliot]

Improve VM property checking for falsy values rather than just missing keys in the Vertex vm dictionary. This is the "proper" way to check a dictionary and will also provide more robust checks.

[mitchnegus]

Food for thought: we could use the setdefault method for most/all of these. It sets the value on a dictionary (and returns the result) if it does not exist in the dictionary already. It is the built-in one-liner for the if/then clauses that we do here, so it seems like it might be the even more "proper" way to do this.

self.vm.setdefault("architecture", "x86_64"):

But also, we started doing this style on the VyOS MC and I didn't think to suggest it then, so also cool with proceeding here.

[mitchnegus]

Food for thought: we could use the setdefault method for most/all of these. It sets the value on a dictionary (and returns the result) if it does not exist in the dictionary already. It is the built-in one-liner for the if/then clauses that we do here, so it seems like it might be the even more "proper" way to do this.

self.vm.setdefault("architecture", "x86_64"):

But also, we started doing this style on the VyOS MC and I didn't think to suggest it then, so also cool with proceeding here.

Actually, nevermind. This would probably be preferable if we were only checking for key existence, like in the original, but it will not catch falsy values. This looks good to me.