Add Buffer indexOf with Limit

[yschimke]

From square/okhttp#8665

Ideally we would have

override fun indexOf(bytes: ByteString, fromIndex: Long, toIndex: Long): Long

[JakeWharton]

Might be better to do #1208 and then all APIs get a free limiter. You can do either limit(1024).indexOf(..) or peek().limit(1024).indexOf(..) to not consume.

[yschimke]

Yep, particularly since @swankjesse publicly promised to rush it. 😁

To celebrate this fun coincidence I shall rush this new API.

[JakeWharton]

I have it on a branch, not that it's all that complicated. The sole impediment was that OkHttp needs to know when you hit the limit. And I can't remember if it also needs a callback when someone closes. The API was getting messy.