* Refactor bytes.go and bytes_test.go to smaller files, introduce go1.17 and go1.20 style of array copy
* rename bytes_go17.go to reflect that it works on any version 1.19 and below
* fix PadTo when len is exactly the size
* Add go1.20 style conversions
* Forgot another int method
Co-authored-by: Radosław Kapka <rkapka@wp.pl>
Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>