Modernize CostFunction and FirstOrderFunction constructors

- Add constructors taking std::unique_ptr and ceres::Ownership to
  AutoDiffCostFunction, NumericDiffCostFunction, and their dynamic
  and first-order counterparts.
- Standardize delegating constructor style to use parentheses.
- Standardize ownership check in destructors.
- Fix documentation typos and example code in headers.
- Add comprehensive tests for Ownership and unique_ptr constructors.

Change-Id: I573abd695cdd89905997b573620e8d99d1cacca2

internal/ceres/dynamic_numeric_diff_cost_function_test.cc

@@ -525,9 +525,19 @@ TEST(DynamicNumericdiffCostFunctionTest, ArgumentForwarding) {
   (void)DynamicNumericDiffCostFunction<MyCostFunctor>();
 }
 
-TEST(DynamicAutoDiffCostFunctionTest, UniquePtr) {
+TEST(DynamicNumericDiffCostFunctionTest, UniquePtr) {
   (void)DynamicNumericDiffCostFunction<MyCostFunctor>(
       std::make_unique<MyCostFunctor>());
 }
 
+TEST(DynamicNumericDiffCostFunctionTest, Ownership) {
+  MyCostFunctor functor;
+  {
+    DynamicNumericDiffCostFunction<MyCostFunctor> cost_function(
+        &functor, DO_NOT_TAKE_OWNERSHIP);
+    cost_function.AddParameterBlock(3);
+    cost_function.SetNumResiduals(3);
+  }
+}
+
 }  // namespace ceres::internal