Features/liquid testnet and wallet creation

[BHodl]

• Adding liquid testnet.
• Adding docker swarm option in docker-compose.yml for the elements section.
• Updating elements version from v0.18.1.12 to v0.21.0.2. This only work if element docker is manually build to latest version or if cyphernode dockerhub update liquid image to the latest version, otherwise the setup will fail. Check PR26 on docker repo.
• Adding liquid wallet creation. Verify if the required liquid wallets are created, otherwise it create it.

Tested and working using docker-compose on testnet except for the the element_unwatch request which give me this error:

2022-04-12T15:52:57+0000 5606 Entering main()... 2022-04-12T15:52:57+0000 5606 [main] line=GET /elements_unwatch/tlq1qqw6quxnga9fq3qycypxs6zhgvf3evpxm6639pfgtt2hvpqwrkslxazdx4tu34sel784asw8kajgs8l04xw7yj7ncgjcj8daeq HTTP/1.0 2022-04-12T15:52:57+0000 5606 [main] cmd=elements_unwatch 2022-04-12T15:52:58+0000 5606 [main] http_method=GET 2022-04-12T15:52:58+0000 5606 [main] step=1 2022-04-12T15:52:58+0000 5606 Entering elements_unwatchrequest()... 2022-04-12T15:52:58+0000 5606 GET 2022-04-12T15:52:58+0000 5606 [elements_unwatchrequest] Unwatch request id GET /elements_unwatch/tlq1qqw6quxnga9fq3qycypxs6zhgvf3evpxm6639pfgtt2hvpqwrkslxazdx4tu34sel784asw8kajgs8l04xw7yj7ncgjcj8daeq HTTP/1.0 on address "" with url0conf "" and url1conf "" 2022-04-12T15:52:58+0000 5606 Entering sql()... 2022-04-12T15:52:58+0000 5606 [sql] psql -qAtX -h postgres -U cyphernode -c "UPDATE elements_watching SET watching=false WHERE id=GET /elements_unwatch/tlq1qqw6quxnga9fq3qycypxs6zhgvf3evpxm6639pfgtt2hvpqwrkslxazdx4tu34sel784asw8kajgs8l04xw7yj7ncgjcj8daeq HTTP/1.0" NOTICE: identifier "tlq1qqw6quxnga9fq3qycypxs6zhgvf3evpxm6639pfgtt2hvpqwrkslxazdx4tu34sel784asw8kajgs8l04xw7yj7ncgjcj8daeq" will be truncated to "tlq1qqw6quxnga9fq3qycypxs6zhgvf3evpxm6639pfgtt2hvpqwrkslxazdx4t" ERROR: syntax error at or near "HTTP" LINE 1: ...wrkslxazdx4tu34sel784asw8kajgs8l04xw7yj7ncgjcj8daeq HTTP/1.0

Can you confirm that element_unwatch request work in your setup using the features/liquid branch?