errors: define error with error code supporting

[kamilsk]

Motivation: Silent error is not enough for a better experience with CLI

cli/errors/silent.go

Lines 7 to 13 in d3a8508

	type Silent interface {
	error
	// Code returns an exit code.
	Code() int
	// Message optionally returns an exit message.
	Message() (string, bool)
	}

. Need to define abstract error with exit code support and ake it useful for go-tool and go-service templates.

To do:

• Support wrap/unwrap/cause: https://github.com/octolab/pkg/blob/19e671e0420f209e9ee8c9294722eeb4d4834cf3/errors/errors.go#L58-L65