Add PV dof and covariance information to functor collections

The original TupleToolGeometry and the likes also provided the user with information about the covariance matrix of the PV or endvertex, along with the NDOF.

Something similar can be achieved through functor composition, such as

        i_cov_matrix = lambda i: F.CALL(i, i) @ F.POS_COV_MATRIX
            "ALLPV_XERR[nPV]": F.MAP(F.SQRT @ i_cov_matrix(0)) @ F.TES(pvs),
            "ALLPV_YERR[nPV]": F.MAP(F.SQRT @ i_cov_matrix(1)) @ F.TES(pvs),
            "ALLPV_ZERR[nPV]": F.MAP(F.SQRT @ i_cov_matrix(2)) @ F.TES(pvs),

for all the PVs in the event.

It would be good if we can restore an option to include this in the functor collections, as the functor composition is rather technical.