flutter_package / fluttertpc_get

- fixes #465
- iOS has an exception to the rule, when no Curve is defined, it doesn't use linearTransition in `CupertinoPages` (`Transition.cupertino/native/default`) and fullscreen dialogs so it applies the Curve, or use the default one.
It might be smarter, maybe, to also enforce the `animation` duration to stay in platforms defaults.
- had to change `CupertinoTransitions.buildTransitions` params in order to make the check and keep the code change small.

- `Changed HashMap<int,GetStateUpdate>` to `HashSet<GetStateUpdate>`.
 Reference https://github.com/jonataslaw/getx/pull/565#discussion_r484088390
-  Added a internal VoidCallback in `GetStateUpdaterMixin::getUpdate`, to see if it reduces overhead of anonym function in `setState()` (considering GC).

- renamed and added defaults transition duration and types in "GetInterfase"
- added missing parameters in `Get.to` / `Get.offAll`,  fixes #570
- added optional `transitionDuration` and `transitionCurve` to `Get.dialog()`

- improved code docs for `BindingsBuilder` clarifying the issue with fat arrows and Get.put()
- major change in `GetxController`, `GetBuilder`, `SimpleBuilder` to improve docs, code cleanup (left a "clean" mess with the previous code to revert if needed)
- new `GetStateUpdaterMixin` and `GetStateUpdate` in favour of `StateSetter` (big change).
- Fixes issue #507, quick code for testing multiple GetBuilder ids can be found here: https://gist.github.com/roipeker/f34654ca35b80f5bf34736bd865f6358.
Warning: is a big change, but I did my tests and seems to be working fine. Please, test performance and potential bugs.

fix(docs): fix page argument in GetPageRoute that needs to be a function

added json support to Rx

Closes #558

resolves the value (for native types) or "toJson()" in custom classes.

[docs] more refactor to dependencies docs

Documentation improvements

Só existia na documentação em inglês

fixes for Controller and improvements with extensions and BindingBuilder.

- fixes the onClose(), onInit() async override in GetxController
- added a shortcut `BindingsBuilder.put()` to register a single Controller in a view.
- fixes some doc comments
- added new extensions for `num` and `duration` to apply delayed calls.

Pela nova ortografia, o prefixo extra só possui hífen se preceder
palavra iniciando por "a" ou "h"

Allows you to insert widgets inside a CustomScrollView

trying to fix git file conflicts, and change example app id/name

very often you have to convert the widget to slivers

Manually modify in /example macos, linux, ios, android to use
package_id: com.getx.GetXDemo
name: GetX Demo