fix: add instantiating indexer status, and display error if instantiation fails

[lostman]

Description

On develop, when indexer instantiation fails, forc index status will display the last status from the database. This may be running, Indexed 12345 blocks.

This PR adds IndexerStatusKind::Instantiating to avoid this situation.

In addition, if the indexer instantiation fails, the status is set to error and a proper message is displayed:

Indexers:

─ fuellabs
   ├─ explorer
   |  • id: 1
   |  • created at: 2023-11-08 11:54:53.323558 UTC (6h 45m ago)
   |  • status: error
   |  • status message:
   |      Error instantiating wasm interpreter: Link(
   |          Import(
   |              "env",
   |              "ff_single_select",
   |              UnknownImport(
   |                  Function(
   |                      FunctionType {
   |                          params: [
   |                              I64,
   |                              I32,
   |                              I32,
   |                          ],
   |                          results: [
   |                              I32,
   |                          ],
   |                      },
   |                  ),
   |              ),
   |          ),
   |      )

Testing steps

1. Check out maciej/1437-entity-find and start the indexer:

   cargo run --bin fuel-indexer -- run --run-migrations --fuel-node-host beta-4.fuel.network --fuel-node-port 80 --replace-indexer --manifest examples/fuel-explorer/fuel-explorer/fuel_explorer.manifest.yaml

2. Check out develop, and restart the indexer without --manifest to keep the incompatible indexer in the database.
3. Run forc index status to see the incorrect status.
4. Check out maciej/add-more-indexer-statuses, and restart the indexer (again, without --manifest).
5. Run forc index status to see the correct status and error.