Support specifying policy configuration inline

[ralphch0]

Currently, admins are required to host a configuration file in order to use the managed config API. The spec mentions that this is useful for configs that are very large. That said, this introduce additional friction for using the feature: Finding somewhere to host a file, generating the hash, etc..
It would be great if we can also support inline configuration: Allow admins to specify the config directly in the managed config policy. I believe this matches how admins generally configure native applications.