sharrow cache clear script

[jpn--]

This pull request introduces improvements to environment variable handling and logging in the main CLI and multiprocessing tasks, as well as adds a new utility script for managing the sharrow cache. The changes help improve debugging, stability, and cache management.

Environment variable handling and logging improvements:

• Added logic in activitysim/cli/main.py to prevent multithreading by setting relevant environment variables based on command-line arguments, improving stability during benchmarking and non-fast runs.
• Introduced the log_environment_info function in activitysim/core/mp_tasks.py, which logs environment variables for debugging if the ASIM_LOG_ENVIRON environment variable is set. This function is now called in mp_run_simulation and check_proc_status to capture environment info during multiprocessing steps. [1] [2] [3]

Codebase maintenance:

• Cleaned up imports in activitysim/core/mp_tasks.py by moving the import of exceptions to the top and removing a duplicate import. [1] [2]

New script for cache management:

• Added other_resources/scripts/clear_sharrow_cache.py, which scans the ActivitySim cache directory for sharrow cache folders and either moves them to a timestamped archive directory or deletes them, depending on the archive parameter.