Add a way to specify arguments

[tgross35]

Could a way to pass arguments to the invocation be added? A way to enable flags like -Dunsound without a configuration file would be great.

Alternatively, maybe something like RUSTSECFLAGS=-Dyanked would be workable

[tgross35]

In fact, I can't even seem to use this action for projects where everything is in a rust/ directory :(