Add all posix standard system utilities as tools

[lmello]

To make gptscript more secure, instead of using sys.exec create a tool for each posix standard system utilities tools and create a tool posix-tools that would allow all of them.

This should allow users to specify which tool they want like patch, ed (for editing files), awk, ls, ln etc.

https://pubs.opengroup.org/onlinepubs/9699919799/

[lmello]

Let me know if you think this is useful if it is, I am interested to work on it.