[client] fix generation of duplicate classes (ExpediaGroup#883)

* [client] fix generation of duplicate classes

We were incorrectly using simple class name for the type lookup as all classes are wrapped in some root type (i.e. `Query.MyClass`) whereas GraphQL type name was just the actual type. We were also incorrectly comparing selection sets as we were not unwrapping selection sets of the children fields.

Fixes: ExpediaGroup#864

* fix caching and correctly compare selection sets of different types

[client 3.x.x] fix generation of duplicate classes (ExpediaGroup#884)

Backport of ExpediaGroup#883 to 3.x.x branch

[client 3.x.x] fix generation of duplicate classes (ExpediaGroup#884)

Backport of ExpediaGroup#883 to 3.x.x branch

Fix issue with GraphQLName on properties (ExpediaGroup#870)

* Fix issue with GraphQLName on properties

* Update integration test

Co-authored-by: Shane Myrick <[email protected]>

[3.x.x][client] Remove duplicate header (ExpediaGroup#867)

* Remove duplicate header

Copy changes over from ExpediaGroup#865 to `3.x.x` branch

* Update GraphQLClient.kt

* Update GraphQLClient.kt

Remove duplicate Accept header: application/json (ExpediaGroup#865)

[build] revert Kotlin version to 1.3.72 (ExpediaGroup#858)

We are hitting some library and plugin issues with incompatibilities between Kotlin versions. Downgrading back to 1.3.72 for now, we will revisit update to 1.4 sometime in the future.

[client] update ScalarConverter to accept any objects (ExpediaGroup#819)

* [client] update ScalarConverter to accept any objects

Custom GraphQL scalars can be serialized as any of the other built-in scalars (i.e. int, float, etc). Changed method signatures to accept `Any` when converting to scalar, and produce `Any` when generating JSON value.

* update docs to match change to any

Include java getters for ignore checks (ExpediaGroup#842)

Co-authored-by: Shane Myrick <[email protected]>

[generator] Nullability additional input checks (ExpediaGroup#829)

* Add additional input test

* Add required list check

* Fix linter

Co-authored-by: Shane Myrick <[email protected]>