Provide stmt name for auto-diff related assert info

[erizmr]

Provide stmt name for auto-diff related assert info for basic_verify

TI_ASSERT_INFO(
          found,
          "IR broken: stmt {} cannot have operand {}."
          " If you are using autodiff, please check"
          " https://docs.taichi.graphics/lang/articles/advanced/"
          "differentiable_programming#kernel-simplicity-rule"
          " If it doesn't help, please report this bug by opening an issue at"
          " https://github.com/taichi-dev/taichi to help us improve."
          " Thanks in advance!",
          stmt->id, op->id);
    }

TI_ASSERT_INFO(stmt->parent == current_block_,
               "stmt({})->parent({}) != current_block({})", stmt->id,
               fmt::ptr(stmt->parent), fmt::ptr(current_block_));