[Feature Request] Toggle boss bar command (appearance per player)

[TsengFayt]

Toggle boss bar appearance per player

A configurable option to let players toggle the hiding or showing of boss bar (mmoxpbar) per player, retained on login.

Description
Currently, there only exists an admin command to unilaterally enable or disable the mmoxpbar as a boss bar for all players. Some players will want the option to disable this for themselves, without the admin turning them off for all players. If players could run a command which sets a value in their mcmmo player data file, which the server checks upon login, then they could save their preferences per player allowing them to choose for themselves to see the mmoxpbar or not.

Functions

• Add a new permission mcmmo.commands.mmoxpbar.toggle which if set to true, allows players to run the command /mcmmo mmoxpbar toggle. This allows admins to decide if players can toggle the xp bar.
• Append a parameter of mmoxpbar-enabled: <true/false> to the playerdata saved by the plugin, which is fetched upon login or when the value is updated by the player using mcmmo mmoxpbar toggle. This would allow them to only need to set it once to keep the setting active on subsequent logins.
• (Optional) Add a placeholder so that admins can add a notification to the motd stating if they player has the bar enabled or disabled to remind the player at login. Example: "mcmmo XP bar is enabled"

Related Issues
This feature has been requested multiple times, I am aware there are already open issues, but they were set to In Progress nearly 5 years ago in 2019 so I chose not to necropost.

There are also various requests for the same thing found in the Discord.

Boss Bar toggle command • #3767