Updated plugin to use placeholder API.

- %stopwatch_time% to get the formatted time as shown in hotbar
- %stopwatch_seconds% to get just the seconds passed in timer


Dev changes:
changed to build plugin using maven instead, updated source code link

Milliseconds are now shown by default and can be disabled by using /st togglems

Added the functionality to let the timer count above one hour and not just wrap back to 0

Now need to add permission stopwatch.default to see message

Added commands /st showall to show timer message to all players (by default) and /st show [playername] to show to specific player

Now should work in ANY version above 1.16 (unless the api changes for ChatMessageType)