Feat: Option to trim whitespace from operation document in generated code

[AnthonyMDev]

For users that want to minimize the payload of their networking requests, we can trim whitespace from the operation document string in the generated operation models.

The QueryStringLiteralFormat option in ApolloCodegenConfiguration has a singleLine case that already formats the string removing new line characters. We could add an associated value of trimWhitespace: Bool to this case to allow trimming all whitespace as well. It would not make sense to add this to the multiLineoption of course, which is why it should be an associated value on singleLine rather than a new standalone configuration option.

This should default to false in order to keep the default inline with the existing implementation and not make changes to generated code for users automatically.