Pay - Sardine On-Ramp

[BellringerQuinn]

Add Sardine On-Ramping capabilities to the SDK

Ridl: https://github.com/0xsequence/stack/blob/master/api/proto/api.ridl#L810

Specifically, we need to integrate the following endpoints:

• SardineGetClientToken -> This is used to generate the on-ramp link
• SardineGetSupportedRegions
• SardineGetSupportedFiatCurrencies
• SardineGetQuote -> This can be used to get a quote for on-ramping (so we can estimate how much it would cost users from within an app)

The most important is SardineGetClientToken

You should also export a function that, given a SardineGetClientToken, returns the on-ramp link - Unity example: https://github.com/0xsequence/sequence-unity/blob/Feature/marketplaceCheckout/Packages/Sequence-Unity/Sequence/SequenceSDK/Pay/Sardine/SardineCheckout.cs#L145

Unity Sardine code can be found here: https://github.com/0xsequence/sequence-unity/tree/Feature/marketplaceCheckout/Packages/Sequence-Unity/Sequence/SequenceSDK/Pay/Sardine
Not all of it is relevant immediately to this ticket, so look for code relevant to those endpoints

Please include BP support