244 marketplace checkout - crypto transactions

[colezemind]

Update Notes

• Marketplace Checkout functions have been integrated for use via Blueprints or C++
• New SequenceCheckoutBP Subsystem available for ease of accessing Checkout functions
• Caveat to the subsystem, user will have to set the ChainID in it prior to invoking Checkout functions. It's a one time thing to also avoid having to set an additional property per Checkout function
• Checkout functions implemented:
  - GetCheckoutOptions
  - GetCheckoutOptionsByOrders
  - GenerateBuyTransaction
  - GenerateSellTransaction
  - GenerateListingTransaction
  - GenerateOfferTransaction
  - GenerateCancelTransaction
  - GenerateCancelTransactionByOrder
• I've created an Actor for testing and showcases uses, it's called BP_CheckoutTesting

Docs Checklist

Please ensure you have addressed documentation updates if needed as part of this PR:

• I have created a separate PR on the sequence docs repository for documentation updates: Link to docs PR
• No documentation update is needed for this change.

[BellringerQuinn]

Already merged into V2 branch