Custom exit code handling

[adamralph]

Use case(s)

Some commands return non-zero exit codes when they succeed. For example, Robocopy:

An Exit Code of 0-7 is success and any value >= 8 indicates that there was at least one failure during the copy operation.

When running such a command, the default exit code handling in SimpleExec may throw an exception when the command succeeds. Custom exit code handling is required for these scenarios.

Description

Run, RunAsync, Read, and ReadAsync have a new optional parameter: Func<int, bool> handleExit. The supplied delegate argument should return true to indicate that it handled the exit code, and that the default exit code handling in SimpleExec should be suppressed, and false otherwise.

For example:

Run("robocopy", handleExitCode: exitCode => exitCode < 8);

Breaking, because handleExitCode was added as an optional parameter before cancellationToken in RunAsync and ReadAsync.

Also deprecates NonZeroExitCodeException in favour of ExitCodeException, since the name of the former doesn't make sense when an argument is supplied to handleExitCode.

Alternatives

Catch and swallow the exception in consuming code when the exit code indicates success.

Additional context

Replaces #298. Thanks to @nixtar for raising that issue.

Depends on #311.

[adamralph]

@nixtar I've released this in 8.0.0-alpha.1 if you want to give it a try.