A bit huge PR, but I couldn't split it into smaller parts because some of the changes need other changes to work, and I don't like to open PRs before I test. The changes include:

• Update MiniPlaceholders version (code is the same, but bytecode had some breaking changes)
• Change names from template/example expansion to player expansion, including package name, to avoid package collisions with other expansions
• Implement paper expansion
• Implement some unimplemented placeholders from MiniPlaceholders wiki
• Removed unused imports
• Add gradle wrapper files
• Replace tabs with spaces in gradle script (it had both tabs and spaces)
• Add supported placeholders to README.md
• Implement <player_locale> in paper for parity