[Add] .compile() uses tmpdir for binary

[g5t]

This pull request updates the Simulation class in simulation.py to improve how temporary directories are handled during compilation. Now, if no directory is specified when calling compile, a temporary directory is automatically created and managed by the Simulation instance, ensuring proper cleanup.

Temporary directory management improvements:

• The compile method now accepts directory=None, in which case a temporary directory is created and its lifetime is tied to the Simulation instance for automatic cleanup. [1] [2] [3]
• Added an instance variable _tmpdir to store the temporary directory object when created.
• Updated the docstring for compile to document the new behavior when directory is None.