Choose the best server by testing responses from multiple server hosts

[true-jared]

Is your feature request related to a problem? Please describe.

It's a terrible experience when the lightwalletd server you're depending upon is down, and you have to manually switch in order to get your wallet to sync.

Describe the solution you'd like

If the lightwalletd server you've selected is not performing well, you should be prompted to switch. The user could also permit automatic switching in the advanced options.

Slack thread: https://zcash.slack.com/archives/C02C1GZ0R6F/p1712083097884379

Solution is to be discussed and determined with the core team.