Importing has to be single threaded since it requires the database lock, but there's nothing to stop us from validating signatures on multiple threads, as no lock is required. So it makes sense to separate these two functions to allow for possible multi threaded signature validation in the future, to speed up the process.
Everything remains single threaded in this commit. It should be functionally the same as before, to reduce risk.
Note: this relies on (a modified version of) liblitewallet-jni which is not included, but will ultimately be compiled for each supported architecture and hosted on QDN.
LiteWalletJni code is based on https://github.com/PirateNetwork/cordova-plugin-litewallet - thanks to @CryptoForge for the help in getting this up and running.
Also removed CrossChainDigibyteACCTv1Resource, since this is unused, and it seems excessive to maintain support of this for every coin (and potentially every ACCT version).
Direct connections for arbitrary data are currently unlikely to succeed, because those allowing incoming connections generally have their slots maxed out and have reached maxPeers. The idea here is that some connections remain reserved for dedicated arbitrary data transfers, therefore temporarily circumventing the limit (up to a defined maximum number of reserved connections).
Arbitrary data connections will auto disconnect after 2 minutes (we might be able to reduce this at a later date), and it also probably makes sense for the requesting node to disconnect as soon as it has all the chunks that it needs (this part isn't implemented yet).
One downside of this feature is that the listen socket is now going to be accepting connections most of the time, since it is unlikely that we will regularly have 4 data peers connected. This could be improved by modifying the OP_ACCEPT behaviour based on whether we are expecting any data peers to connect. In most cases, this would allow it to remain closed. But for the sake of simplicity I will leave that optimization for a future commit.
This is used to force a quick disconnect for peers that are only connecting for the purposes of requesting data for a specific arbitrary transaction signature.
