Support scanning multiple id's for extension.

[jcblw]

Description

To support multiple vendors ( Chrome, Firefox, Edge, or Safari ) you would need to handle multiple ids for this to work with external messaging. You could do something like user-agent sniffing to get the correct vendor and send the specific id but it would be nicer if there was a way to scan for active ids. This could be something like passing a list of ids to finches context.

<ExtensionProvider scanIds={[x,y,z]}>...</ExtensionProvider>

The extension provider will make a built-in query to a finch API.

query healthcheck {
  _healthcheck
}

Then when something responds to this we could store some state into the provider that extension is responding to queries.

Think there could be weird issues when multiple respond probably not terrible though.