Deprecate legacyResponse and prepare for partial/incremental caching

[calvincestari]

The cacheWriteInterceptor currently relies on doing an inefficient double-parsing of the received response to get the cache records for a cache write. This is incompatible with partial and incremental responses. Instead we should capture the cache records during the first response parsing and store them for the CacheWriteInterceptor to use later in the chain.

[calvincestari]

Closing this as it was completed with the merging of apollographql/apollo-ios-dev#337.

[github-actions]

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