Add benchmarks for serializing model with complete schema

[alexmojaki]

As suggested in #1093 (comment)

[codspeed-hq]

CodSpeed Performance Report

Merging #1189 will improve performances by 25.62%

_{Comparing serialize-benchmark (014ae2f) with main (61a6562)}

Summary

⚡ 3 improvements
✅ 143 untouched benchmarks

🆕 2 new benchmarks

Benchmarks breakdown

	Benchmark	main	serialize-benchmark	Change
🆕	test_complete_core_serializer_to_json	N/A	1.2 ms	N/A
🆕	test_complete_core_serializer_to_python	N/A	1 ms	N/A
⚡	test_core_future	37.8 µs	30.1 µs	+25.62%
⚡	test_tuple_many_positional	42.8 µs	34.2 µs	+25.13%
⚡	test_tuple_many_variable	42.7 µs	34.2 µs	+24.93%