Macro run_make_support::impl_common_helpers

macro_rules! impl_common_helpers {
    ($wrapper: ident) => { ... };
}

Implement common helpers for command wrappers. This assumes that the command wrapper is a struct containing a cmd: Command field and a output function. The provided helpers are:

1. Generic argument acceptors: arg and args (delegated to Command). These are intended to be fallback argument acceptors, when specific helpers don’t make sense. Prefer to add new specific helper methods over relying on these generic argument providers.
2. Environment manipulation methods: env, env_remove and env_clear: these delegate to methods of the same name on Command.
3. Output and execution: output, run and run_fail are provided. output waits for the command to finish running and returns the process’s Output. run and run_fail are higher-level convenience methods which waits for the command to finish running and assert that the command successfully ran or failed as expected. Prefer run and run_fail when possible.

Example usage:

struct CommandWrapper { cmd: Command } // <- required `cmd` field

impl CommandWrapper {
    /// Get the [`Output`][::std::process::Output] of the finished process.
    pub fn command_output(&mut self) -> Output { /* ... */ } // <- required `command_output()` method
}

crate::impl_common_helpers!(CommandWrapper);

impl CommandWrapper {
    // ... additional specific helper methods
}