accounthist should read from blockstream

[Matthew Darwin]

accounthist should read from blockstream (when running live) instead of only reading from files.

accounthist/injector/pipeline.go <-- injector's 'source' is set directly to a FileSource, not a JoiningSource

You can see log messages like this:

(accounthist) reading from blocks store: file does not (yet?) exist, retrying in (bstream/filesource.go:179){"filename": "0101689300.dbin.zst", "base_filename": "0101689300", "retry_delay": "4s", "secondary_blocks_stores_count": 0}