Network Indexer Status - remove outdated entries

[sondreb]

The list of indexers and their status is not removing any entries if they disappear and is no longer active/available. The wallet will continue to attempt to check the status of these indexers. We should consider removing (and instead re-adding) entries that have been "offline" for X amount of time.

[sondreb]

This was added as a means to manually reset the network status cache and trigger an refresh of status for all indexers:

[sondreb]

Now the list of indexers is retrieved from nameservers, so out-of-date indexers likely won't be listed in the network status view.