Remove transformed queries

[martinbonnin]

Now that #1841 is merged, this PR can be merged.

This PR:

• removes the transformed queries as operationOutput.json contains more data
• makes operationOutputFile a RegularFileProperty instead of a DirectoryProperty
• adds OperationOutput(File) to transform OperationOutput.json to data structures easier to work with. There an exemple in the integration tests: https://github.com/apollographql/apollo-android/compare/master...martinbonnin:remove-transformed-queries?expand=1#diff-2966339ccc9c3f57b884f0a635458863R12. Would that be ok ?

[martinbonnin]

Instead of using transformedQueriesDir with a flat dir of all transformedQueries, you would now have to use operationOutputFile that is a json that maps operationIds to transformedQueries.

You can use OperationOutput(file: File) to create pojos from the json file.

@DSteve595 is it ok for you ?

[DSteve595]

Sounds great. Thank you all for your hard work.

[tasomaniac]

I have very small comments. Thanks for taking care of this. It definitely keeps the API surface cleaner.

[tasomaniac]

Looks good. Btw, is this a breaking change?

[martinbonnin]

I guess it's a breaking change to whoever is relying on transformed queries. It doesn't change anything to the runtime and/or codegen. Overall, I would say users of transformed queries are advanced enough to migrate to operation output but it's definitely worth a mention in the changelog.

[tasomaniac]

I guess mention in the changelog would be enough. Their build configuration will fail to find the old property. It's a really simple change to fix it.