Add ability to use texture url in /skull

[TheLukeGuy]

Information

This PR closes #3804.

Details

Proposed feature:

This lets users provide custom skins when using the /skull command by specifying a skin identifier instead of a username. This feature is only available on specific versions of Spigot 1.18.1 and above because it uses the new player profile API. On older versions, only a username can be used.

The /skull command now supports the following values in the first argument:

• A username, like before
• The 64-character-long identifier of a custom skin (the last part of the skin URL)
• The 180-character-long base64 value of a custom skin

The first 7 characters of the skin identifier will be used for the skull's display name and the success message. An error message will be sent if a base64 value isn't a valid skin object.

Environments tested:

OS: Windows 11

Java version: openjdk version "17.0.1" 2021-10-19

• Most recent Paper version (1.19.2, git-Paper-189)
• CraftBukkit/Spigot/Paper 1.12.2
• CraftBukkit 1.8.8

Demonstration:

I used this head as an example. The screenshot below was taken immediately after running the following commands (and switching my hotbar slot in between):

/skull 1c1df3b095e6a774e26852901db234003979c7a75ce35d8d269bb3651e09cfa2
/skull eyJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHA6Ly90ZXh0dXJlcy5taW5lY3JhZnQubmV0L3RleHR1cmUvMWMxZGYzYjA5NWU2YTc3NGUyNjg1MjkwMWRiMjM0MDAzOTc5YzdhNzVjZTM1ZDhkMjY5YmIzNjUxZTA5Y2ZhMiJ9fX0=

[mdcfe]

Thanks for the PR! Overall this looks good, but it would be great if you could add an additional command usage message to indicate that texture URL hashes are accepted.

[TheLukeGuy]

Sounds good! Does this look alright? I'm not sure I like the wording of it too much, but I can't think of any better way to describe it.

[mdcfe]

Apologies for the delay in re-reviewing this! The new usage message looks good.

This PR will need updating and conflicts resolving before it can be merged. If you get a chance to do this, it would be great, but if not we can resolve this before we merge it.

[TheLukeGuy]

All good, sure! I'll get the conflicts resolved as soon as possible.