feat: make policy length limits configurable per engine (#624)

- Add PolicyLengthConfig struct with max_col, max_file_bytes, and
  max_lines fields, replacing hardcoded constants in the lexer.
- Add Engine::set_policy_length_config and clear_policy_length_config
  to allow callers to override the default limits.
- Add Source::from_contents_with_limits and from_file_with_limits for
  direct Source construction with custom limits; existing from_contents
  and from_file signatures are preserved using defaults.
- Add tests for default rejection, custom limits, and engine plumbing.
- Add bindings for C, C++, Python, WASM/JS, Java, Ruby, C#, Go

bindings/go/main.go

@@ -18,6 +18,8 @@ func main() {
 	defer engine.Close()
 
 	engine.SetRegoV0(true)
+	// Raise the default col limit to 2000
+	engine.SetPolicyLengthConfig(regorus.PolicyLengthConfig{MaxCol: 2000, MaxFileBytes: 1048576, MaxLines: 20000})
 	elapsed1 := time.Since(t)