encoding.TextUnmarshaler not supported on koanf.Unmarshaled

[genofire]

Describe the bug
Custom Datetypes (like for time, data unit) are not Unmarshaled (on yaml).
Therefore is https://pkg.go.dev/encoding#TextUnmarshaler defined and

To Reproduce

type DataUnit int64

func (d *DataUnit) UnmarshalText(text []byte) error {
	var magnitude float64
	s := strings.ToLower(string(text))
	switch {
	case strings.HasSuffix(s, "tb"):
		s, magnitude = s[:len(s)-2], 1024*1024*1024*1024
	case strings.HasSuffix(s, "gb"):
		s, magnitude = s[:len(s)-2], 1024*1024*1024
	case strings.HasSuffix(s, "mb"):
		s, magnitude = s[:len(s)-2], 1024*1024
	case strings.HasSuffix(s, "kb"):
		s, magnitude = s[:len(s)-2], 1024
	default:
		magnitude = 1
	}
	v, err := strconv.ParseFloat(s, 64)
	if err != nil {
		return err
	}
	*d = DataUnit(v * magnitude)
	return nil
}

func TestUnmarshalDataUnit(t *testing.T) {
	target := struct {
		Got DataUnit `config:"value"`
	}{}
	for input, expect := range map[string]DataUnit{
		"value: 0.6tb": 659706976665,
		"value: 1.2gb": 1288490188,
		"value: 256mb": 268435456,
		"value: 128kb": 131072,
		"value: 128":   128,
	} {
		k := koanf.New("/")
		if err := k.Load(rawbytes.Provider([]byte(input)), yaml.Parser()); err != nil {
			t.Fatal(err)
		}
		if err := k.UnmarshalWithConf("", &target, koanf.UnmarshalConf{Tag: "config"}); err != nil {
			t.Fatal(err)
		} else if target.Got != expect {
			t.Fatalf("expected value %d but got %d", expect, target.Got)
		}
	}
}

Test failed:

--- FAIL: TestUnmarshalDataUnit (0.00s)
    config_test.go:295: 1 error(s) decoding:
        
        * cannot parse 'value' as int: strconv.ParseInt: parsing "256mb": invalid syntax
FAIL
FAIL	github.com/matrix-org/dendrite/setup/config	0.012s
FAIL

Expected behavior
Defined Test works

[genofire]

default decoder should contain more Hooks, like:

mapstructure.ComposeDecodeHookFunc(
				mapstructure.StringToTimeDurationHookFunc(),
				mapstructure.StringToSliceHookFunc(","),
				mapstructure.TextUnmarshallerHookFunc())

in

koanf/koanf.go

Line 242 in ed3461c

mapstructure.StringToTimeDurationHookFunc()),

---

mainly mapstructure.TextUnmarshallerHookFunc() would solve the problem.