Align on common parameter pattern for specifying graph and variant

[abernix]

As of https://github.com/apollographql/rover/releases/tag/v0.0.1-rc.0 there are variations in the way that "graph + variant" are provided as rover parameters. For example, the rover schema fetch command expects a <GRAPH_NAME> positional parameter with a --variant flag:

$ rover schema fetch
error: The following required arguments were not provided:
    <GRAPH_NAME>

USAGE:
    rover schema fetch <GRAPH_NAME> --log <log-level> --profile <profile-name> --variant <variant>

... while the rover partial delete command expects a --graph-name and a --graph-variant as flagged parameters (with no positional parameters):

$ rover partial delete
error: The following required arguments were not provided:
    --graph-name <graph-name>
    --service-name <service-name>

USAGE:
    rover partial delete --graph-name <graph-name> --log <log-level> --profile <profile-name> --service-name <service-name> --variant <variant>

... and the rover schema push command (which is in the same subcommand categorization as rover schema fetch in the first example from above), expects similarly flagged parameters but a <SCHEMA_PATH> as the lone positional parameter:

$ ./target/debug/rover schema push --help
rover-schema-push 0.0.1-rc.0
⬆️  Push a schema to Apollo Studio from a local file

USAGE:
    rover schema push [OPTIONS] <SCHEMA_PATH> --graph-name <graph-name>

I actually believe that rover schema fetch is the outlier here but, if <graph-name> is as important as I think it is to most of the commands in the partial and schema commands, I would claim that it should be the model and that we should always have the <graph-name> as the first positional parameter.

Thoughts? Discussion? (If this issue is closed and we resolve this later, we should at least align on one pattern, which I think means fixing rover schema fetch.)

[JakeDawkins]

Closing because I didn't see this and started conversation on the duplicate #101 🤦