feat: add experimental finder option

Signed-off-by: Mark Sagi-Kazar <mark.sagikazar@gmail.com>

finder.go

@@ -13,6 +13,13 @@ func WithFinder(f Finder) Option {
 	})
 }
 
+// ExperimentalFinder tells Viper to use the new Finder interface for finding configuration files.
+func ExperimentalFinder() Option {
+	return optionFunc(func(v *Viper) {
+		v.experimentalFinder = true
+	})
+}
+
 // Finder looks for files and directories in an [afero.Fs] filesystem.
 type Finder interface {
 	Find(fsys afero.Fs) ([]string, error)

viper.go

@@ -194,6 +194,8 @@ type Viper struct {
 	// TODO: should probably be protected with a mutex
 	encoderRegistry *encoding.EncoderRegistry
 	decoderRegistry *encoding.DecoderRegistry
+
+	experimentalFinder bool
 }
 
 // New returns an initialized Viper instance.