This adds settings to each provider to allow us to control if individual
fallback items are enabled or not, regardless of the provider being
enabled.
This is relevant to _all the threads where disabling fallback commands
came up_
This just adds another section to each provider's settings page, with a
list of the fallback commands.
This also has nothing to do with the "top-level apps search", which is
not really a fallback command - it's its own thing.
Ref #38288. Doesn't close that, because this only controls
enable/disable, not ranking.
From here, we should be able to add a dedicated page in the SUI that
shows all the fallbacks across all providers. That's where we'll enable
the ordering.
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