Delete all resources when deleting indexer

[morgsmccauley]

Deleting the indexer from the UI will only remove it from the registry contract, but all the infrastructure resources will remain. The following should be deleted along with the registry entry:

• Related redis keys
• Hasura configuration
• Database schema

Tasks

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1. Expose endpoint from Runner to control provisioning #759
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2. Handle provisioning within Coordinator #760
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3. De-provision resources on Indexer deletion #761
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4. Clean up previously deleted indexers #792
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[morgsmccauley]

This may be tricky with Coordinator viewing the snapshots of the Registry at single points in time. Coordinator compares the registry to the system directly, so will only know of a deletion if the system is actually running that deleted indexer, but if we restart during a deletion, the event will be missed.

We may need to introduce some persistent state which Coordinator can refer to as to gain more awareness of these events.

[morgsmccauley]

Another perhaps more straight forward approach would be to query Hasura/Postgres to the current provisioning state, which could be compared to the registry. This removes the need for capturing specific point-in-time events, and allows us to simply synchronise actual/desired states exactly like we are for Block streams/Excutors.