Xendit iOS Support

[farhanfadila1717]

Hi @salkuadrat this PR included iOS support for xendit.
And both modified in dart and Android side,
some modified in dart side because in iOS i'm found diffrent callback from android version xendit

[fahami]

I see your PR add amount as required field in createMultipleUseToken method, while the origin fxendit are not. Is this a new rule from xendit or any reason for this @farhanfadila1717 ?

[farhanfadila1717]

@fahami it's aged PR, my project use other options to using in app payment with xendit. This PR i'm only wrap iOS xendit plugin with Flutter Methodchannel, i'm actually forgot why amount is required

[fahami]

@fahami it's aged PR, my project use other options to using in app payment with xendit. This PR i'm only wrap iOS xendit plugin with Flutter Methodchannel, i'm actually forgot why amount is required

Ok then, thanks for clarifying @farhanfadila1717. Anyway, can you share what is the other options you are using in order to achieve in app payment with xendit, if you don't mind? are you using in-app webview?