Add support for Embedded Payment Element

[programmeraditya]

Is your feature request related to a problem? (please describe)
No.

Describe the solution you'd like
React Native SDK v0.46.0 added support for Embedded Payment Element, but it's not yet implemented in the Flutter SDK.

Describe alternatives you've considered
N/A

Additional context
Docs: https://docs.stripe.com/payments/elements/in-app-payment-element

[programmeraditya]

@jonasbark I am working on this myself. I am using this PR as source: #2235 as it has been synced with v0.53.1.

[tara-pogancev]

Hello @programmeraditya ! I see that this PR has been merged. May I ask if this now means we will be able to use the Payment Element, with all additional supported payment types out of the box (e.g. PayPal, CashApp, etc.) along with cards and Google/Apple payment we had thus far? If so, do you know when would the new package version be available to use?

Thank you for your contribution! 😄

[programmeraditya]

Hello @tara-pogancev ! The PR is not related to the changes I am working on. To be more specific, when I started working on it, the PR was not merged, the main branch had synced up to React Native SDK version v0.46.0 only, so I started making changes on the sync branch (which the PR was from) as it already synced with version v0.53.1.

Regarding the progress, I am happy to share I was able to get it working on Flutter, and it supports all payment methods that the React Native SDK supports. There are some layout and design issues as which I am working on. I will create a PR soon.

[programmeraditya]

Here's the PR.
#2239

Note that I only tested the iOS implementation properly. The Android integration may not work as it is. I would appreciate if anyone helps finish the Android side.

[programmeraditya]

Android implementation is also complete. With this the embedded payment element feature has been mirrored fully from the React Native SDK.
Would appreciate feedback.
PR: #2239
Thanks!

[tara-pogancev-levi9-com]

This is amazing work! I will look into testing the feature on both Android and iOS, and report here. :)