Warn/error about unsupported flags

[JustinDrake]

Unsupported command line flags are silently ignored. For example, truffle test --unsupportedgarbage will ignore the --unsupportedgarbage flag.

I suggest warning about such flags, or maybe even erroring out.

[CruzMolina]

Requirements

1. When truffle is passed an unsupported command line flag, it should throw a helpful error.

Example:

truffle test --unsupportedFlag

Error: `truffle test` does not currently support the `--unsupportedFlag`.
Please see https://truffleframework.com/docs/truffle/reference/truffle-commands
for currently supported command flags.

2. Add an integration mocha test to verify proper error handling.

Prerequisite Context

• Familiarity with the current entry point for Command handling: https://github.com/trufflesuite/truffle/blob/develop/packages/truffle-core/lib/command.js. In particular these lines.
• Familiarity with current truffle command integration tests, i.e. https://github.com/trufflesuite/truffle/blob/develop/packages/truffle-core/test/commands.js.

[eggplantzzz]

Should this throw an error or perhaps just a warning?

[eggplantzzz]

This has been fixed for a while now. Closing this for issue maintenance.