And make this also available to the cli, so the uuid's generated from the cli match the correct world uuids where possible.

For spigot-worlds there is a uid.dat file that can be read.
For sponge-worlds this can be read from the level_sponge.dat
For worlds that don't have a uuid, bluemap should maybe create an own uuid-file in the world-folder

Implemented in 2.0.
The uid is not read from the files, but bluemap generetes and uses it's own id and stores it in a bluemap.id file in the world-folder.