Add logging features to improve observability

[AkshatMittal7]

This PR introduces logging features to the PTY library to enhance observability and ease debugging. The changes include:

1. Added logging statements to key functions:

   • Pty::new
   • take_fd
   • pty_resize
   • set_close_on_exec
   • set_nonblocking

2. Introduced a new is_active method to check PTY state.

3. Enhanced error messages in take_fd and pty_resize functions.

4. Added an init_logging function to allow users to easily initialize logging.

5. Added instructions on how to run tests with logging on

These changes will help developers using this library to:

• Better understand the flow of operations within the PTY
• More easily diagnose issues in production environments
• Have a clearer picture of the PTY's state at any given time

Testing:

• Added logging statements can be verified by running tests with RUST_LOG=debug

Dependencies added:

• log = "0.4"
• env_logger = "0.10"

This PR aims to improve the maintainability and debuggability of the library without changing its core functionality.