Copper is not upgraded correctly from pre-21w05a worlds

Copper blocks aren't upgraded correctly when loading a pre-21w05a world in 21w05a. Some blocks disappear, and the fully weathered copper blocks revert into the penultimate weathered block stage. This is because the blocks were renamed and the block IDs were changed, but the upgrade paths weren't adjusted to accomodate that. This also affects their item forms.

To reproduce

1. Load this world in 21w03a: 2021-02-03_19-53-19_Ghost Copper.zip
2. Upgrade it to 21w05a
   → Some blocks are missing and the fully weathered blocks have jumped back a stage