Initialize LogAddressIndexProvider from the Transform

[sduchesneau]

• BasicLogFilter (implementing interface Transform) should implement a new method, ~GetIndexProvider() that will utlimately be called from the firehose (returns the provider, or nil if anything goes wrong)

• in cmd/sfeth/cli/firehose.go, when registering the BasicLogFilterFactory, it should be pre-loaded (using a FactoryFactory :tm: ) with the index store and the indexSizes array.

• in bstream and maybe the firehose package, you need to check if GetIndexProvider is implemented via a new interface, and call it on your transforms (see the transformReg.BuildFromTransforms method, that generates a preprocessor, now you need the same mechanism to generate an index)

• What to do if more than one tranform generates an index ? panic for now..... or maybe just use one of them.

[froch]

[sduchesneau]

@froch the https://github.com/streamingfast/streamingfast-client (command sf eth ...) can run a request against a local firehose with transforms.