refactor(tarko): merge EditFileRenderer into DiffRenderer

[ulivz]

Summary

Merged redundant EditFileRenderer into DiffRenderer to consolidate diff rendering functionality. The EditFileRenderer was only used for str_replace_editor content, while DiffRenderer handled standard diff format. Now DiffRenderer handles both cases:

• str_replace_editor content with old/new content comparison (previously edit_file type)
• Standard unified diff format content (existing diff_result type)

Updated str_replace_editor renderer condition to use diff_result instead of edit_file type.

Checklist

• Added or updated necessary tests (Optional).
• Updated documentation to align with changes (Optional).
• Verified no breaking changes, or prepared solutions for any occurring breaking changes (Optional).
• My change does not involve the above items.

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