proposal: strings,bytes: add ReplaceOnce

### Proposal Details

as there many usage of Replace(old, new, 1).
I Proposal to add ReplaceOnce to strings and bytes package. Like wise ReplaceAll.
```
func ReplaceOnce(s, old, new string) string {
	return Replace(s, old, new, 1)
}
```
```
func ReplaceOnce(s, old, new []byte) []byte {
	return Replace(s, old, new, 1)
}
```