Rework api code generation (#16)

[chippmann]

• feature/rework-api-code-generation: Done using kotlin Poet to generate constructors

• feature/rework-api-code-generation: Add Enums and Signals generation using KotlinPoet

• feature/rework-api-code-generation: rework dirty for loops

• feature/rework-api-code-generation: Generate casts with Kotlin poet

• feature/rework-api-code-generation: Add constants generation

• feature/rework-api-code-generation: Generate singletons' rawMemory property with KotlinPoet

• feature/rework-api-code-generation: Add properties generation with Kotlin Poet

• feature/rework-api-code-generation: Rework methods generation with Kotlin Poet

• feature/rework-api-code-generation: Use Kotlin Poet to generate iCalls, fixed miss imported classes and methods

• feature/rework-api-code-generation: Several fixes, sucessfully compiled gdnative library

• feature/rework-api-code-generation: remove former generation code

• feature/rework-api-code-generation: Add todo to move dependency version declaration to buildSrc

• feature/rework-api-code-generation: rework code formatting

• feature/rework-api-code-generation: Change formatting

• feature/rework-api-code-generation: Replace for loop with foreach loop

• feature/rework-api-code-generation: Rename ind to index

Co-authored-by: Pierre-Thomas Meisels meisels27@yahoo.fr, Cedric Hippmann cedric.hippmann@hotmail.com