Item: make setter methods fluent

[SmallkingDev]

Make Item setter methods fluent

API Changes

• Updated the return types of the following Item setter methods to $this:
  • setCanPlaceOn
  • setCanDestroy
  • setKeepOnDeath

Example:

Before:

$item = VanillaItems::DIAMOND_PICKAXE();
$item->setCanPlaceOn([]);
$item->setCanDestroy([]);
$item->setKeepOnDeath(true);

After:

$item = VanillaItems::DIAMOND_PICKAXE()
    ->setCanPlaceOn([])
    ->setCanDestroy([])
    ->setKeepOnDeath(true);

[dktapps]

These changes are BC breaking for inheritors if they override any of these functions

[SmallkingDev]

These changes are BC breaking for inheritors if they override any of these functions

The chance of someone doing this must be slim, but it's a valid concern.

[dktapps]

Semver doesn't care about chances, objectively it is BC breaking, so it can't target a minor version.