Resolves #3160

Summary

This prevents us from:

• copying the incoming API data causing __typename to be applied to output data by default
• reusing incoming API data and treating it as equivalent to Graphcache’s owned data

In short, we don't differentiate in the cacheExchange whether we're passing query() previous Graphcache data or API data. This data is then used to diff against the new result, reusing as much of it as possible when it's unchanged. It's also used to complete the output data when some cache resolution fails, to fall back to API data.

However, we shouldn't reuse this data blindly when it's API data, since that data can slightly differ and carry __typename fields even when those aren't specified in the selection set.

Set of changes

• Replace originalVariables with better operations.set tracking
• Stop copying original data when creating “owned” data
• Only reuse original data when it's previously “owned” data, and otherwise consider it changed
• Add “foreign data” flag to initDataState
• Remove operations helper usage in cacheExchange and intead call initDataState and clearDataState manually
• Clean up usage of operations/*