Allow per player creative mode checks

[S-S-X]

From issue #267

Allow using per player check for all creative mode checks.

Technic minimum required engine version is 5.0 and this API function is only available in 5.3 so make it use minetest.is_creative_enabled(name) only if it is available.

Also technic.creative_mode probably can't be simply changed to be API function as this will break checks in many other mods, Technic mod should probably still have its own wrapper for creative mode checks for compatibility.

[S-S-X]

Optionally bump up minimum required engine version, I think this might have been discussed before too.