[feat]: Add support for AssumeUTXO (starting with Bitcoin Core v28)

[fjahr]

Prerequisites

• I have searched for existing issues that already suggest this feature.

Describe the Feature Request

AssumeUTXO allows for a Bitcoin Core node to be usable faster by loading a recent UTXO set snapshot and syncing from there. Full IBD still happens, but later and in the background. See https://github.com/bitcoin/bitcoin/blob/master/doc/design/assumeutxo.md and bitcoin/bitcoin#28553. I am happy to answer questions about usage if the documentation is not clear.

The mainnet parameters were recently merged so support will be available starting with the release of v28 (ca. October), you can track it here: bitcoin/bitcoin#29891.

Describe the Use Case

Start9 nodes could be usable much faster because users don't have to wait for the full IBD to finish, especially if the used computer is underpowered.

Describe Preferred Solution

No response

Describe Alternatives

No response

Anything else?

No response

[MattDHill]

Transferred to correct repository. Now that StartOS 040 imminent, we can look into getting this implemented in a nearterm release of Bitcoin