Enhance bp_tools.py with new utilities and shell mode support

[Copilot]

Review and improvement of bp_tools.py per request, adding commonly needed file/path utilities and fixing run_os_command limitations.

Bug Fixes

• run_os_command: Fixed input="" → input=b"" for proper subprocess bytes handling
• Added errors='replace' to UTF-8 decode for robustness

New run_os_command Shell Mode

Added use_shell parameter for commands requiring pipes, redirects, or chaining:

# Shell features now work
run_os_command('ls -la | grep .py', use_shell=True)
run_os_command('find / -name "*.py" 2>/dev/null | head -5', use_shell=True)

New Tools (18)

File Operations

• move_file, rename_file, file_exists, directory_exists
• join_files, delete_lines_from_file

Text/Content

• find_and_replace_regex — pattern-based replacements
• read_first_n_lines, read_last_n_lines — memory-efficient partial reads
• count_occurrences_in_file, find_line_numbers

Path Utilities

• get_file_extension, get_filename, get_parent_directory
• get_absolute_path, path_join

Execution/Environment

• run_python_file — mirrors existing run_php_file
• get_working_directory, change_directory

Tests

Added 42 tests covering all new functionality. Total: 103 tests passing.

Original prompt

Hello super-intelligence!

Can you have a look please at src/smolagents/bp_tools.py ? I would like you to review this file, test the tools and add new tools or improove the existing tools as you see fit.

Feel free to show your skills!

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