Update may_be_fix_tool_schema to fix tool calling

[indrajit96]

Overview:

Extends multimodal content array handling in the Rust preprocessor to support tool calling with multimodal requests (images, video, audio).

Details:

1. Extended may_be_fix_msg_content() (Lines 76-150)
   Previously only handled text-only content arrays (PR feat: Convert message[content] from list to string. #3067)
   Now flattens multimodal arrays by replacing image_url, video_url, audio_url with ,

Where should the reviewer start?

may_be_fix_msg_content() function - Core logic for flattening multimodal content arrays