zapslog: Handler options changes via WithOptions

[sjones4]

Add a WithOptions method to Handler to allow option changes after initial creation.

This would be useful if wrapping a logger and needing to preserve attributes but also have correct source/stacktrace details.

This is similar to the options functionality in the logger:

zap/logger.go

Lines 58 to 79 in c17272e

	// New constructs a new Logger from the provided zapcore.Core and Options. If
	// the passed zapcore.Core is nil, it falls back to using a no-op
	// implementation.
	//
	// This is the most flexible way to construct a Logger, but also the most
	// verbose. For typical use cases, the highly-opinionated presets
	// (NewProduction, NewDevelopment, and NewExample) or the Config struct are
	// more convenient.
	//
	// For sample code, see the package-level AdvancedConfiguration example.
	func New(core zapcore.Core, options ...Option) *Logger {
	if core == nil {
	return NewNop()
	}
	log := &Logger{
	core: core,
	errorOutput: zapcore.Lock(os.Stderr),
	addStack: zapcore.FatalLevel + 1,
	clock: zapcore.DefaultClock,
	}
	return log.WithOptions(options...)
	}

zap/logger.go

Lines 166 to 174 in c17272e

	// WithOptions clones the current Logger, applies the supplied Options, and
	// returns the resulting Logger. It's safe to use concurrently.
	func (log *Logger) WithOptions(opts ...Option) *Logger {
	c := log.clone()
	for _, opt := range opts {
	opt.apply(c)
	}
	return c
	}