Remove istringstream and ostringstream from Position

[EarlyEdition]

The idea of removing (istringstream,ostringstream) was taken from Ronald de Man on Cfish repository.

There were three patterns as follows:

• string& -> char*

- string& fenStr

+ char* fenStr

• Remove istringstream

- ss >> token;

+ token = *fenStr++; 

• Remove ostringstream

- ss << 'Q';

+ *str++ = ('Q');

The flip() function is the only thing left! And i'll do it soon, too.

[github-actions]

clang-format 17 needs to be run on this PR.
If you do not have clang-format installed, the maintainer will run it when merging.
For the exact version please see https://packages.ubuntu.com/mantic/clang-format-17.

(execution 9021517668 / attempt 1)

[Disservin]

What is the purpose of this? I see no value in going back to raw c strings.. obviously in a c project you dont have istringstream so you remove it..

[Disservin]

We are not trying to minimize number of includes though. Stockfish is written in C++ so we might as well use C++