deletes TreeGridRowGroup component in favor of subtree slot
The component is problematic for the virtualization scenario (as for virtualization libraries the rendering should be flattened, with all components in the same level and with TreeGridRowGroup this is not possible)
TreeGridRowGroup
component in favor ofsubtree
slotTreeGridRowGroup
this is not possible)subtree
slot (although not an ideal syntax) is predictable and simpler to usesubtree
slotreact-window
as devDependencyTODO
@fluentui-contrib/react-tree-grid-react-window
?!