Silence Nearby Mobs

Inspired by the "Vanilla Tweaks" datapack which goes well with this datapack. Adds the following commands:

• /trigger silence: mutes all mobs within 8 blocks.
• /trigger unsilence: unmutes all mobs within 8 blocks.
• /trigger set_silence_immune [​set] [​amount]: sets an amount of the nearest mobs to be immune to silence (if [​set] [amount]) isn't used, it will set only 1.
• /trigger unset_silence_immune [​set] [​amount]: unsets an amount of the nearest mobs to be immune to silence (if [​set] [amount]) isn't used, it will unset only 1.