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/cpp/main.cpp

@@ -8,6 +8,13 @@ void example()
 
     engine.set_rego_v0(true);
     engine.set_enable_coverage(true);
+
+    RegorusPolicyLengthConfig len_config;
+    // Raise the default col limit to 2000
+    len_config.max_col = 2000;
+    len_config.max_file_bytes = 1048576;
+    len_config.max_lines = 20000;
+    engine.set_policy_length_config(len_config);
     
     // Add policies.
     engine.add_policy("objects.rego",R"(package objects