Remove cursor logic from sink

[DenisCarriere]

• [x] remove reading & writing cursor directly in sink
  • Some sinks will need to validate the incoming data before saving the cursor, saving the cursor prior to validation can cause data loss
• [x] export fileCursor & httpCursor

import { setup, fileCursor } from "substreams-sink"

...
// Get cursor from file
const cursor = fileCursor.readCursor("cursor.lock");

// Setup sink for Block Emitter
const { emitter } = await setup({...options, cursor});
...
// Save new cursor on each new block emitted
fileCursor.onCursor(emitter, "cursor.lock");

• [x] remove --http-cursor-auth & --cursor-path params
• [x] add --cursor param
• [x] remove startCursor from setup
  • cursor is already provided as setup input
• [x] update logging output