Support File or In-line for Cost Model or Variables

[joesixpack]

To be consistent with the cost variables, have cost moodel support in-line json instead of reading a file. Or have both support reading files.

[czarly]

how about this? Is this helpful?

graph indexer cost set variables <subgraph_id> $(cat globals.json)

[koen84]

@czarly that's a workaround. I agree it would be good to have built-in support.