Re-design probe selection when creating / editing checks

[ckbedwell]

What would you like to be added: To reevaluate and update the design for selecting probes when creating and editing checks. Currently the multi-select pattern doesn't help a huge amount for visibility of what is available or help group the probes in any meaningful way.

It would be ideal if we could find a way to display all of the probes simultaneously and also in a way where they are organised by region and/or cloud provider.

Why is this needed: Users may want to pick probes based on their region and/or cloud provider. At the moment they have to go back and forth to different parts of the app and documentation to gather all of that information.

Additional context Issue for the synthetic-monitoring-api to provide the cloud provider information in the probes list endpoint.