CG-11840: Optimize ListDirectoryTool performance using os.listdir()

[codegen-sh]

Description

This PR optimizes the ListDirectoryTool to use os.listdir() instead of the slower directory.files() approach. This addresses the performance issue identified in the Slack conversation where the tool was taking up to 90 seconds to execute on large codebases like ramp/core.

Changes

• Modified get_directory_info() in list_directory.py to use os.listdir() and os.path.isfile() to get file listings
• Changed subdirectory traversal to use recursive=False to avoid unnecessary recursion
• Added error handling for file system operations
• Added import for the os module

Expected Performance Improvement

This change should significantly improve the performance of the ListDirectoryTool by:

1. Avoiding the creation of full file objects for each file in the directory
2. Using native file system operations which are much faster
3. Reducing unnecessary recursive operations

Related Issue

Fixes issue mentioned in Slack conversation about slow performance with ramp/core codebase.

Linear Ticket

Related to CG-11840

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