Set lnd alias to OpenDEX alias

[kilrau]

Currently the lnd alias is set to the first 20 chars of its pubkey. We would want to set it to OpenDEX: followed by the OpenDEX alias, e.g. OpenDEX: LaundryBrush.

Main goal is to increase visibility for OpenDEX on lightning network explorers like 1ml.com

[kilrau]

And since LND pubkey/Alias <-> XUD Pubkey/Alias are clearly visible and can be queried when running a xud node, I dont think this changes much from a privacy perspective.

An alternative would be setting from 20charsOfLndPubkey to sth like 20charsOfLndPubkey (OpenDEX), so one could guess that a particular lightning node is used within OpenDEX from explorers like 1ml, but one would have to go through the hazzle to run an OpenDEX node and run a query finding the particular OpenDEX node for the lightning node.

[kilrau]

Problems:

• lnd's are created before xud (meaning we can't know about the xud alias yet)
• changing alias requires lnd restart to take affect. Which could have unintended side effects at xud runtime since orders could be up/swap in progress.
• we should avoid overwriting any personalized alias a user set
• ideally OpenDEX alias could be applied to existing environments

Idea:

• add this check on unlock within xud-docker: if lnd alias == first 20 chars of pubkey, then overwrite with OpenDEX: Alias if not (meaning it was personalized) do nothing. If a change to one or more lnd alias' was applied, restart this/these lnds. Since xud was just unlocked, orders can't be up yet or will have to wait until lnd's are back up. Drawback: this adds complexity and might slow down the unlock procedure. Thoughts?