Log user data size

[randomvariable]

/kind feature

Related to #705

Describe the solution you'd like
Add a log output at a suitable level of verbosity that states the size of the userdata when g'zipped and prior to base-64 encoding.

This will allow us to determine the pace at which we need to find an alternative solution to packing files and X.509 cryptographic material into the userdata.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster-api-provider-aws version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[liztio]

/assign