new implementation for string split

Hello So I have been working on string split and wrote my own and its faster than boost implementation of split

[source code](https://github.com/adnan007d/string-split-cpp.git)

I was hoping to contribute the same in boost :smile:

Start by reviewing the linked source repository and the existing Boost string-splitting implementation. Compare the reported performance and determine the intended API, compatibility expectations, tests, and benchmarks needed before proposing an implementation. Done would require an agreed design and evidence that the Boost contribution is faster without regressions.

Written by the indexing model from the issue text.