Fixes issue 1566 (Show popup if local Bitcoin core is running)

[ManfredKarrer]

See bisq-network/bisq#1566

[cbeams]

utACK. This looks fine as-is, but I've noticed that if my Bitcoin Core node is not fully synced, that Bisq falls back to connecting to Bisq's federation of nodes. This is basically fine from a privacy perspective (assuming the user trusts our nodes), but it always surprises me when it happens, and it would be nice (I think) if Bisq gave me some kind of heads up that it's going to fall back to the federation, with the choice of letting it go ahead or quitting Bisq while waiting for my Bitcoin node to finish syncing. Not saying that we need to hold up this PR at all; just wanted to put this out there, since I'd been thinking about it lately anyway, and because it's related to this change.

See also my review comment at #118 (review) regarding avoiding creating a separate issue and pull request pairs where a single pull request would suffice. Thanks.

[ManfredKarrer]

I have not investigated it more closely but from my experience it connects to Bitcoin core while syncing. Maybe it depends on the current sync state of Bitcoin core? Bisq basically just try to connect to localhost on the default port and if it can connect it assumes Bitcoin Core is running.
In one of the next versions the UI will have the option to set pruned mode in Bitcoin Core and then more people might get that problem (as reported from a user who could not get Bisq synced as he had a pruned node running).
Its a more complex topic in all as pruned nodes could still provide data depending on the depth of the pruning and the age of the Bisq wallet... No clear idea how to deal with that and I doubt we can detect that...

[ghost]

I have the same issue with Bisq from time to time:
The list of BTC peers is full ... while the list of Bisq peers is empty.
And my first reaction is ... why is Bisq able to connect to the BTC network, but not to its own network ?
(I have no BTC node running. Just sometimes Torbrowser open).

I profit to mention that, generally, Bisq connects with 8 BTC peers, while the window list is only 5 items high, which implies:

• one cannot see all the peers at a glance
• one must scroll, just for 3 rows
  And same remark for the Bisq P2P list.

[ripcurlx]

utACK