feat: implement `From<assert:cmd::Command>` for `process::Command`

[mcky]

Allows conversion with process::Command::from(asserted_cmd)

As mentioned in #212 I was having trouble serializing the value of the inner std::process::Command.

After this PR the following should be possible:

let cmd = Command::cargo_bin(env!("CARGO_PKG_NAME"))
let std_cmd = process::Command::from(cmd)

[epage]

Not sure what I think of this as its a lossy operation.

[mcky]

Would you be open to any API that exposed the underlying std::process::Command?

[epage]

Would you be open to any API that exposed the underlying std::process::Command?

What value is using assert_cmd::Command giving you if you are then immediately wanting a std::prcoess::Command?

[mcky]

Many of my other tests use cargo_bin and the success/fail/stdout/stderr assertions via helpers, but for the odd interactive test I’m having to use rexpect instead, and being able to get at the internal cmd would save reworking them all.

Of course I don’t expect this merger just for my convenience, I just thought it might be generally useful to expose it in some manner (e.g. a getter or marking it public)

[epage]

Considering we provide

• cargo_bin
• CommandCargoExt
• OutputOkExt
• OutputAssertExt

it seems like if a std::process::Command is needed, assert_cmd shouldn't be in the way, so I'm not seeing a reason to move forward with this.