Add file input support for large arguments in `blockstack-cli` `contract-call` hex function args

[BowTiedRadone]

The blockstack-cli contract-call command currently doesn't support reading function arguments from files, which becomes a limitation when working with large hex data inputs. For example, when attempting to pass large hex serialized data (>1MB) as an argument using -x, the command fails with "Argument list too long" due to shell limitations.