implement refreshonly for all types

Use Case

refreshonly is useful in some edge-cases to ensure that resources are only managed in a particular situation. It is awkward to implement in the core API and impossible in a Resource API provider.

See ini_setting.rb#L132 for a simple, but broken implementation example

Describe the Solution You Would Like

See resource_api.rb#L382 for a start to implement it.

likely should look like this:

def flush
  real_flush unless refresh_only
end

def refresh
  real_flush if refresh_only
end

with the current flush's contents moved to {{real_flush}}, and the refreshonly attribute getting automatically defined, and all the bells and whistles of actually properly building this instead of a jira sketch.

Describe Alternatives You've Considered

This could also be implemented as a basic feature for all types in core puppet.

Additional Context

Originally filed as https://tickets.puppetlabs.com/browse/PDK-1217

Start by reading resource_api.rb around line 382 and compare it with the refreshonly example in ini_setting.rb around line 132. Trace how flush and refresh are handled for Resource API types, then define completion as refreshonly being automatically available and correctly controlling whether changes are applied across all types, including the documented edge cases.