Function ExtractGlobPattern 

fn ExtractGlobPattern(Pattern: &Value) -> Option<String>

Extract a glob string from any of the shapes a caller can hand us:

• Bare string: "**/*.rs" → returned as-is.
• Object with pattern: { pattern: "..." } (or { base, pattern } for VS Code’s RelativePattern).
• Object whose value field is a string: legacy serialised form.