Text Placeholder API

First release for new cycle! Includes bunch of refactors and renames and intruduces support for common and client placeholders!

For migration, most notable changes: What previously was PlaceholderContext was moved to ServerPlaceholderContext, and alike (ParserBuilder changed placeholders() -> serverPlaceholders()) for those who want previous features. Renamed getText and alike to getComponent. TextNodes are still TextNodes through.

Full Changelog: https://github.com/Patbox/TextPlaceholderAPI/compare/2.8.1+1.21.10...3.0.0-beta.1+26.1