Separate "sequence similarity" and "tree-guided" grouping modes in MSA editor

Today we use a single boolean variable to differentiate grouping (collapsible) mode in MSA Editor: bool virtualOrderMode.

When this mode is 'false' the MSAEditor uses row order from the MSA file and has no collapsible groups.

When this mode is 'true' the MSAEditor is either in the 'order-and-group-by-sequence-content' or in the 'order-and-group-like-a-tree' mode.

There is no way to differentiate between the latter 2 modes today and it is impossible to react correctly to MSA changes in this case.

These 2 virtual modes must be differentiated and it should allow fixing tree-sync related crashes found after re-enabling tree-sync mode recently.