Keeps variants with mean(Freq) >= mean_count_cutoff across rows in @GTsummary.filtered,
enforces a minimum number of rows per variant, updates @V.fitered, and rebuilds
matrices and depth matrix.
Usage
filter_redeemR_by_meancount(
redeemR_obj,
mean_count_cutoff = 2,
min_cells_per_variant = 2,
QualifiedTotalCts = NULL,
filter_name = NULL
)