Beyond The End - Compass

    Run structure compass searches off the server thread
    findNearestMapStructure ran synchronously inside StructureCompassItem#use.
    A search walks up to 100 rings of placement cells and, for every candidate,
    may run the structure's full generation check (whole jigsaw layout) and
    load/generate chunks up to STRUCTURE_STARTS, so the server froze for
    seconds (much longer when nothing is found) and every extra right click
    started another frozen search.

        - New StructureLocator: uses Async Locator (already in the modpack, called
          through reflection, so it is not a hard or compile dependency) to search
          on its own thread and hands the result back on the server thread. Falls
          back to the old synchronous search when Async Locator is missing.
        - The compass goes on cooldown while searching (removed when done, then a
          1 s cooldown), so only one search per player can be running.
        - The result is written to the compass that started the search, found by
          a per-search id even if it was moved to another slot; the dimension is
          the one where the search started.

    Move compass distance HUD above the held item name

    The distance text was drawn at screenHeight - 60, overlapping the vanilla
    held item name (screenHeight - 59). Draw it at screenHeight - 84, above
    the item name and the action bar (screenHeight - 72 .. - 63) where the
    compass "searching/found" messages are shown.