18.2.0-alpha.8

8b4e68785 [FIX] chart: label header prevents creating linear/time charts Task: 4543496
e76ab4485 [FIX] chart: fix test clicking on wrong checkbox Task: 4543496
08e13e18b [FIX] UUID: Reduce uuid size everywhere except revisions Task: 4532659
008ff74c8 [FIX] formulas: SORTN is not exported anymore Task: 4564445
db0276cf7 [FIX] collaborative: recompute selection after concurrent sheet modifications Task: 4559104
97b42329b [IMP] css: remove global content-box directive Task: 4550753
02cd2b6fb [IMP] xlsx: support xlsx file type variants Task: 4492696
25096c371 [FIX] collaborative: fix undo concurrence issues Task: 4558024