Figure out where/when to register license key for Anka

[ldx]

At some point (maybe when building AMI? or when itzo starts up?) the license key for Anka needs to be registered.

[hidalgopl]

I guess this issue is becoming a blocker now
EDIT: not a blocker, but for production use, we need to figure it out.
. From what we observed so far, activating license on one mac instance and creating an AMI doesn't work, as newly created instance with this AMI has license invalid.
Here's my idea for implementing it:

1. User sets ankaLicenseKey once inside the provider.yaml in kip (could be a part of cellConfig).
2. Kip adds anka_license file containing only license key value to itzo dir using same mechanism that is already used for deploying certs etc.
3. Itzo should try to activate license key before running anka VM. This can be done in mac runtime implementation of RunPodSandbox method. If activating fails, itzo shouldn't try to run a VM, and fail early with clearly distinguishable reason for end user.

I'd rather have it as a part of mac runtime instead of forcing user to setting this as a part of cloudinit.yaml.

As this requires changes in both kip and itzo, it can be easily done in parallel. Kip changes can be tested on any instance (not necessarily mac1.metal), which is also convenient.

@ldx @jrroman @henryprecheur let's discuss whether this solution is optimal.