Although raw provider resources accept an input that allows a user to
specifiy a provider version to use, this input is not reflected in
current SDK code generation. Furthermore, we already have a method to
specify the provider version that should be used for a resource: the
"version" resource option. These changes update the code that handles
provider resource registrations to autmoatically populate the version
input from the "version" resource option if the option is present.
Fixes https://github.com/pulumi/pulumi-azure/issues/803.