Add destructuring bindings to Tengo

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What this task asks for

Add destructuring bindings for `:=` in arrays, maps, and function parameters. Add destructuring bindings with `:=`. Map patterns bind by key, including shorthand `{x}` and renaming `{x: a}` (with optional defaults like `{x: a = 50}`). Rest elements (`...name`) collect remaining array elements and must appear last in the pattern. Default values (`name = expr`) evaluate lazily and apply only when a position or key does not exist in the source. Only `:=` triggers destructuring. Compile-time errors must include these substrings: `rest element must be last`, `cannot use destructuring with =`.