Follow the renames from the review of the view builder

The review of #5620 renamed document_data's tape/tape_size/tape_cap to
nodes/node_count/node_capacity and made the decode arena a
std::vector<char>; adapt the code of this change to it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

single_include/nlohmann/json_view.hpp

@@ -4604,7 +4604,7 @@ class basic_json_view
     /// decoded strings); the estimate sizes the output buffer of dump()
     std::size_t source_extent() const noexcept
     {
-        const node* const end = m_doc->tape + m_doc->tape_size;
+        const node* const end = m_doc->nodes + m_doc->node_count;
         if ((m_node->flags & detail::view::node_flags::storage) != 0)
         {
             return m_node->len;