[9/n] [sync-switch] bail on an incomplete bootstore config instead of silently dropping items

[sunshowers]

Previously, on encountering a transient DB issue, we would silently drop items from the bootstore config. That seems quite obviously bad and was part of the reason #10640 escalated a crdb bug into persistent bootstore corruption.

Rework all this by:

• collecting all the problems that occurred
• returning a new error type if there were any problems

This is a functional change that is worth thinking very hard about. Many but not all of the invariants here are maintained by the database layer. If there's persistent db corruption or a similar issue, we will no longer generate a bootstore config for the rack! I think this is overall the right thing to do, but it is quite possible there are latent issues that were being hidden by the looser error handling that this code previously had.

The report is now logged by the background task, unless the task exits with one of the other early errors. (There's a much larger rework of the task that needs to be done, but I'm not doing that here since it'll collide with a lot of what @jgallagher is currently doing.)

Depends on:

• [1/n] [sync-switch] build bootstore bgp peers from already-loaded port settings #10642
• [2/n] [sync-switch] move bootstore config building into nexus-switch-config #10643
• [3/n] [sync-switch] move bfd and address lot reads back to bg task, make the builder pure #10644
• [4/n] [sync-switch] replace db-model builder inputs with domain types #10645
• [5/n] [sync-switch] extract db translation into a new crate #10646
• [6/n] [sync-switch] factor switch_port_settings_get body out #10647
• [7/n] [sync-switch] add single-transaction switch config read (not yet wired up) #10648
• [8/n] [sync-switch] read switch config in one transaction #10649