Remove deprecated item stack serde methods

This includes serialising and deserialising item stacks with the default
Jankson instance from JanksonFactory.

These were deprecated in 8.0.0 as they didn't include item components.
Components can't be included in JanksonFactory.builder() since they need
registry access, so devs should use the vanilla item stack codecs instead.

Update Gradle

Update publishing details to be more generic

Update Jankson to 1.2.3, MC to 1.20.1

Update to 1.19.4 and Jankson 1.2.2

Add GH workflow for building

Remove jcenter and mavenLocal from settings.gradle plugin repositories