feat: add Tonkeeper provider

[Ikari-Shinji-re]

Summary

Integrate a Tonkeeper provider:
https://tonkeeper.com

How did you test this change?

Connect the Tonkeeper provider in the widget or playground app and execute a TON transaction.

Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Implemented a user interface (UI) change, referencing our Figma design to ensure pixel-perfect precision.

[yeager-eren]

TonConnect has support for most the TON wallets. So we decided to use that as of our only TON provider.